Vol. 13/ Núm. 2 2026 pág. 2526
https://doi.org/10.69639/arandu.v13i2.2354
Spaced Repetition to Improve Vocabulary Retention in A2-
Level EFL
Repetición espaciada para mejorar la retención de vocabulario en inglés de nivel A2
Gissela Mabel Gorozabel Monge
gmgorozabelm@ube.edu.ec
https://orcid.org/0009-0007-0214-0268
Universidad Bolivariana del Ecuador
Ecuador - Durán
Frelly María Molina Pinargote
fmmolinap@ube.edu.ec
https://orcid.org/0009-0000-2686-4497
Universidad Bolivariana del Ecuador
Ecuador - Durán
Jacqueline Elizabeth López López
jelopezl@ube.edu.ec
https://orcid.org/0000-0002-1765-8103
Universidad Bolivariana del Ecuador
Ecuador - Durán
Josué Reinaldo Bonilla Tenesaca
jrbonilla@ube.edu.ec
https://orcid.org/0000-0002-6748-2345
Universidad Bolivariana del Ecuador
Ecuador -Durán
Artículo recibido: 17 mayo 2026- Aceptado para publicación:28 junio 2026
Conflictos de intereses: Ninguno que declarar.
ABSTRACT
The process of teaching and learning English as a foreign language in Ecuador at the public
secondary education level faces difficulties, especially in relation to medium-term retention. The
overall objective of the study was to determine the efficiency of spaced repetition in English
vocabulary retention in A2-level EFL students at a public educational institution in Portoviejo,
Ecuador. The study was conducted using a quantitative approach. The research design was quasi-
experimental, pretest–posttest design with a control group. The sampling process was intentional
non-probabilistic, for a total of 70 students (35 experimental group and 35 control group). The
intervention was carried out with spaced repetition activities applied over six weeks. Two data
collection instruments were used: an objective test and a Likert-type questionnaire to assess
learning perceptions. Descriptive and inferential statistics were used to analyse the results, using
the analysis of covariance (ANCOVA) procedure. When initial performance was adjusted, the
results indicated that vocabulary retention improved more clearly in the experimental group,
although the effect of spaced repetition was conditioned by students’ initial vocabulary level.
Vol. 13/ Núm. 2 2026 pág. 2527
After the intervention, greater internal consistency was noted in learning perceptions. Spaced
repetition was consolidated as an effective pedagogical method for optimising vocabulary
memorisation in A2-level students. Similarly, an improvement was observed when activities were
carried out in educational environments with limited instruction time, if differences in students'
initial knowledge were considered.
Keywords: spaced repetition, vocabulary retention, English as a foreign language,
secondary education, lexical learning
RESUMEN
El proceso de enseñanza y aprendizaje del inglés como lengua extranjera en ecuador a nivel de
educación secundaria pública enfrenta dificultades, especialmente en relación con la retención a
mediano plazo. El objetivo general del estudio fue determinar la eficiencia de la repetición
espaciada en la retención del vocabulario en inglés en estudiantes de EFL de nivel A2 de una
institución educativa pública de Portoviejo, Ecuador. El estudio se desarrolló bajo el enfoque
cuantitativo. El diseño de investigación fue cuasi-experimental, pretest–postest y grupo de
control. El proceso de muestreo de tipo no probabilístico intencional, para un total de 70
estudiantes (35 grupo experimental y 35 grupo control). La intervención se desarrolló con
actividades de repetición espaciada aplicadas durante seis semanas. Se aplicaron dos instrumentos
de recolección de datos: una prueba objetiva y un cuestionario tipo Likert, para evaluar las
percepciones de aprendizaje. Se utilizó la estadística descriptiva e inferencial para el análisis de
resultados, mediante el procedimiento de análisis de covarianza (ANCOVA). Cuando el
desempeño inicial fue ajustado, los resultados indicaron que la retención de vocabulario mejoró
con mayor claridad en el grupo experimental, aunque el efecto de la repetición espaciada estuvo
condicionado por el nivel inicial de vocabulario de los estudiantes. Después de la intervención,
se notó una mayor consistencia interna en las percepciones de aprendizaje. La repetición
espaciada se consolidó como un método pedagógico eficaz para optimizar la memorización de
vocabulario en los alumnos de nivel A2. De igual manera, se pudo determinar una mejora al
desarrollarse actividades en ambientes educativos con tiempo de instrucción limitado, siempre y
cuando se considere las diferencias en el conocimiento inicial de los estudiantes.
Palabras clave: repetición espaciada, retención de vocabulario, inglés como lengua
extranjera, educación secundaria, aprendizaje léxico
Todo el contenido de la Revista Científica Internacional Arandu UTIC publicado en este sitio está disponible bajo
licencia Creative Commons Atribution 4.0 International.
After the intervention, greater internal consistency was noted in learning perceptions. Spaced
repetition was consolidated as an effective pedagogical method for optimising vocabulary
memorisation in A2-level students. Similarly, an improvement was observed when activities were
carried out in educational environments with limited instruction time, if differences in students'
initial knowledge were considered.
Keywords: spaced repetition, vocabulary retention, English as a foreign language,
secondary education, lexical learning
RESUMEN
El proceso de enseñanza y aprendizaje del inglés como lengua extranjera en ecuador a nivel de
educación secundaria pública enfrenta dificultades, especialmente en relación con la retención a
mediano plazo. El objetivo general del estudio fue determinar la eficiencia de la repetición
espaciada en la retención del vocabulario en inglés en estudiantes de EFL de nivel A2 de una
institución educativa pública de Portoviejo, Ecuador. El estudio se desarrolló bajo el enfoque
cuantitativo. El diseño de investigación fue cuasi-experimental, pretest–postest y grupo de
control. El proceso de muestreo de tipo no probabilístico intencional, para un total de 70
estudiantes (35 grupo experimental y 35 grupo control). La intervención se desarrolló con
actividades de repetición espaciada aplicadas durante seis semanas. Se aplicaron dos instrumentos
de recolección de datos: una prueba objetiva y un cuestionario tipo Likert, para evaluar las
percepciones de aprendizaje. Se utilizó la estadística descriptiva e inferencial para el análisis de
resultados, mediante el procedimiento de análisis de covarianza (ANCOVA). Cuando el
desempeño inicial fue ajustado, los resultados indicaron que la retención de vocabulario mejoró
con mayor claridad en el grupo experimental, aunque el efecto de la repetición espaciada estuvo
condicionado por el nivel inicial de vocabulario de los estudiantes. Después de la intervención,
se notó una mayor consistencia interna en las percepciones de aprendizaje. La repetición
espaciada se consolidó como un método pedagógico eficaz para optimizar la memorización de
vocabulario en los alumnos de nivel A2. De igual manera, se pudo determinar una mejora al
desarrollarse actividades en ambientes educativos con tiempo de instrucción limitado, siempre y
cuando se considere las diferencias en el conocimiento inicial de los estudiantes.
Palabras clave: repetición espaciada, retención de vocabulario, inglés como lengua
extranjera, educación secundaria, aprendizaje léxico
Todo el contenido de la Revista Científica Internacional Arandu UTIC publicado en este sitio está disponible bajo
licencia Creative Commons Atribution 4.0 International.
Vol. 13/ Núm. 2 2026 pág. 2528
INTRODUCTION
In education systems with a longer tradition of foreign language teaching, learning English
was treated as a gradual process, sensitive to time and memory (Masache-Escobar & Enciso,
2023). In Europe, Asia and North America, vocabulary was no longer understood as an
accumulation of isolated words (Namaziandost et al., 2023). It was assumed to be the core that
underpins linguistic comprehension and production in real contexts of use (Li, 2025).
International research showed a constant concern for the fragility of lexical learning (Alisoy
& Sadigzade, 2025). Teaching words did not guarantee their permanence. Many students passed
immediate assessments and, weeks later, were unable to recall the same content (Namaziandost
et al., 2020). This phenomenon led to a rethinking of traditional teaching practices focused on
immediate repetition and accelerated content coverage (Lee et al., 2021).
In this context, spaced repetition was analysed as a strategy aligned with the principles of
human memory functioning (Zhang, 2025). The technique proposed reviewing information at
carefully planned, progressive intervals (Alhazmi, 2024). The aim was to reinforce the memory
trace before forgetting became consolidated. Experimental studies conducted on different
continents reported that this approach allowed for more stable retention and more accurate
retrieval of learned vocabulary (Wang & Lee, 2021).
Educational programmes aligned with international language reference frameworks
incorporated this strategy with consistent results. Evidence showed that improvement did not
depend on increasing the number of words taught. It depended on how time was managed (Li,
2025). This finding generated interest in contexts where instruction time is limited, but the
demand for results remains high (Al-Khasawneh, 2023).
In Latin America, teaching English as a foreign language was incorporated as an
educational policy in secondary education (Cajas & Cherres, 2024). The region adopted common
reference frameworks to define levels of proficiency (Acosta et al., 2022). The objective was
clear: to enable students to communicate in English in a basic and functional way.
The reality showed a clear gap between the curriculum's intention and the results obtained.
Several regional studies pointed out that vocabulary was one of the main obstacles to linguistic
progress. Students learned new words regularly. However, they quickly forgot them. Learning
lacked stability (Vargas-Saritama & Celi, 2024).
The prevailing teaching practices explained part of the problem. Instruction focused on the
initial presentation of vocabulary. Subsequent reviews were scarce. Time was treated as a neutral
variable. This omission had visible consequences on medium-term retention (Parra et al., 2024).
Colombia, Chile, and Brazil began experimenting with distributed revision strategies.
These initiatives were based on models developed on other continents. Their application,
however, was limited. Most studies were conducted in higher education or in contexts with
INTRODUCTION
In education systems with a longer tradition of foreign language teaching, learning English
was treated as a gradual process, sensitive to time and memory (Masache-Escobar & Enciso,
2023). In Europe, Asia and North America, vocabulary was no longer understood as an
accumulation of isolated words (Namaziandost et al., 2023). It was assumed to be the core that
underpins linguistic comprehension and production in real contexts of use (Li, 2025).
International research showed a constant concern for the fragility of lexical learning (Alisoy
& Sadigzade, 2025). Teaching words did not guarantee their permanence. Many students passed
immediate assessments and, weeks later, were unable to recall the same content (Namaziandost
et al., 2020). This phenomenon led to a rethinking of traditional teaching practices focused on
immediate repetition and accelerated content coverage (Lee et al., 2021).
In this context, spaced repetition was analysed as a strategy aligned with the principles of
human memory functioning (Zhang, 2025). The technique proposed reviewing information at
carefully planned, progressive intervals (Alhazmi, 2024). The aim was to reinforce the memory
trace before forgetting became consolidated. Experimental studies conducted on different
continents reported that this approach allowed for more stable retention and more accurate
retrieval of learned vocabulary (Wang & Lee, 2021).
Educational programmes aligned with international language reference frameworks
incorporated this strategy with consistent results. Evidence showed that improvement did not
depend on increasing the number of words taught. It depended on how time was managed (Li,
2025). This finding generated interest in contexts where instruction time is limited, but the
demand for results remains high (Al-Khasawneh, 2023).
In Latin America, teaching English as a foreign language was incorporated as an
educational policy in secondary education (Cajas & Cherres, 2024). The region adopted common
reference frameworks to define levels of proficiency (Acosta et al., 2022). The objective was
clear: to enable students to communicate in English in a basic and functional way.
The reality showed a clear gap between the curriculum's intention and the results obtained.
Several regional studies pointed out that vocabulary was one of the main obstacles to linguistic
progress. Students learned new words regularly. However, they quickly forgot them. Learning
lacked stability (Vargas-Saritama & Celi, 2024).
The prevailing teaching practices explained part of the problem. Instruction focused on the
initial presentation of vocabulary. Subsequent reviews were scarce. Time was treated as a neutral
variable. This omission had visible consequences on medium-term retention (Parra et al., 2024).
Colombia, Chile, and Brazil began experimenting with distributed revision strategies.
These initiatives were based on models developed on other continents. Their application,
however, was limited. Most studies were conducted in higher education or in contexts with
Vol. 13/ Núm. 2 2026 pág. 2529
specific technological support. Public secondary education continued to show a notable absence
of rigorous quantitative evidence (Alvarez et al., 2024).
In Ecuador, English as a foreign language was established as a compulsory subject within
the national curriculum (Salgado et al., 2019). Teaching was aligned with international standards
of linguistic competence. However, despite this regulatory framework, results in public
institutions continue to show limitations in students’ English performance (Esquivel-Gámez &
Berthely-Barrios, 2025). Vocabulary is one of the most affected components. In Portoviejo,
Manabí, this situation is particularly relevant because English teaching is limited to three hours
per week. As a result, students have few opportunities to practise and review the language outside
the classroom, which restricts systematic reinforcement of lexical content (Tamayo et al., 2023).
The students benefiting from this study took the A2 level of EFL at Unidad Educativa ‘18
de Octubre’. They were between 13 and 15 years old. They were at a stage of cognitive
development that was still unstable. Study habits were not well established. Their contact with
English depended almost entirely on what happened in class (Vargas-Saritama & Celi, 2024).
Observation of the context revealed a recurring pattern. Vocabulary was understood in the
short term. After a few weeks, it disappeared. The words did not return. Systematic review was
not part of the teaching plan. Time was not treated as a teaching ally (Cajas & Cherres, 2024;
Parra et al., 2024).
No local experimental studies were identified that analysed this problem using controlled
quantitative designs. The absence of empirical data limited informed decision-making. If this
situation persisted, the risk was clear. Students would advance to the next level with accumulated
lexical gaps that would be difficult to correct at later stages (Alisoy & Sadigzade, 2025).
Based on the picture described above, the following research question was posed:
To what extent did the application of spaced repetition influence English vocabulary
retention in A2-level EFL students at Unidad Educativa ‘18 de Octubre’ in Portoviejo, Manabí?
The question was formulated from a quantitative approach. The focus was on estimating
the effect of a specific pedagogical strategy on a measurable learning outcome. The overall aim
of the study was to determine the efficiency of spaced repetition in English vocabulary retention
in A2-level EFL students. The specific objectives were to assess lexical retention before and after
the intervention, apply spaced repetition activities adapted to the A2 level, and compare the results
between an experimental group and a control group.
Based on the objectives set, the following hypotheses were established:
Alternative hypothesis (H1): A2 students who received spaced repetition showed
significantly higher vocabulary retention, measured by the post-test score adjusted for the pre-
test, compared to students who received traditional instruction.
specific technological support. Public secondary education continued to show a notable absence
of rigorous quantitative evidence (Alvarez et al., 2024).
In Ecuador, English as a foreign language was established as a compulsory subject within
the national curriculum (Salgado et al., 2019). Teaching was aligned with international standards
of linguistic competence. However, despite this regulatory framework, results in public
institutions continue to show limitations in students’ English performance (Esquivel-Gámez &
Berthely-Barrios, 2025). Vocabulary is one of the most affected components. In Portoviejo,
Manabí, this situation is particularly relevant because English teaching is limited to three hours
per week. As a result, students have few opportunities to practise and review the language outside
the classroom, which restricts systematic reinforcement of lexical content (Tamayo et al., 2023).
The students benefiting from this study took the A2 level of EFL at Unidad Educativa ‘18
de Octubre’. They were between 13 and 15 years old. They were at a stage of cognitive
development that was still unstable. Study habits were not well established. Their contact with
English depended almost entirely on what happened in class (Vargas-Saritama & Celi, 2024).
Observation of the context revealed a recurring pattern. Vocabulary was understood in the
short term. After a few weeks, it disappeared. The words did not return. Systematic review was
not part of the teaching plan. Time was not treated as a teaching ally (Cajas & Cherres, 2024;
Parra et al., 2024).
No local experimental studies were identified that analysed this problem using controlled
quantitative designs. The absence of empirical data limited informed decision-making. If this
situation persisted, the risk was clear. Students would advance to the next level with accumulated
lexical gaps that would be difficult to correct at later stages (Alisoy & Sadigzade, 2025).
Based on the picture described above, the following research question was posed:
To what extent did the application of spaced repetition influence English vocabulary
retention in A2-level EFL students at Unidad Educativa ‘18 de Octubre’ in Portoviejo, Manabí?
The question was formulated from a quantitative approach. The focus was on estimating
the effect of a specific pedagogical strategy on a measurable learning outcome. The overall aim
of the study was to determine the efficiency of spaced repetition in English vocabulary retention
in A2-level EFL students. The specific objectives were to assess lexical retention before and after
the intervention, apply spaced repetition activities adapted to the A2 level, and compare the results
between an experimental group and a control group.
Based on the objectives set, the following hypotheses were established:
Alternative hypothesis (H1): A2 students who received spaced repetition showed
significantly higher vocabulary retention, measured by the post-test score adjusted for the pre-
test, compared to students who received traditional instruction.
Vol. 13/ Núm. 2 2026 pág. 2530
Null hypothesis (H0): There were no statistically significant differences in vocabulary
retention, measured by the post-test score adjusted for the pre-test, between A2 students who
received spaced repetition and those who received traditional instruction.
MATERIALS AND METHODS
Research Focus
The study was conducted under a quantitative approach, as its purpose was to measure
the effect of spaced repetition on English vocabulary retention through numerical evidence
obtained before and after the intervention. This approach was appropriate because the research
sought to compare the performance of two groups, estimate changes in vocabulary retention, and
test hypotheses using descriptive and inferential statistical procedures (Mendoza et al., 2021). The
independent variable was the application of spaced repetition as a pedagogical strategy, while the
dependent variable was vocabulary retention in A2-level EFL students. Therefore, the
methodological structure was aligned with the need to determine whether systematic review at
planned intervals produced measurable differences in students’ lexical performance (Bruhn,
2021).
Type and design of research
The research followed a quasi-experimental pretest–post-test design with a non-
equivalent control group. This design was selected because the study was conducted in a real
school context, where random assignment of students was not feasible. For this reason, the
research worked with two intact class groups: one experimental group and one control group
(Alisoy & Sadigzade, 2025). Both groups were assessed before and after the intervention in order
to compare their vocabulary retention levels over time.
The experimental group received instruction supported by spaced repetition activities,
whereas the control group continued with the usual English teaching process without a systematic
review schedule. The pretest made it possible to identify the initial vocabulary level of both
groups, while the post-test allowed the study to estimate the changes observed after the six-week
intervention. This design was appropriate because it enabled the comparison of group
performance while statistically controlling for initial differences through covariance analysis
(Creswell, 2021).
Population and sample
The study was conducted at Unidad Educativa “18 de Octubre”, located in Portoviejo,
Manabí, Ecuador. The institution offers English as a foreign language at the secondary education
level, within a curricular structure aligned with the communicative goals established for public
education. The target population consisted of A2-level EFL students enrolled in secondary
education during the academic period in which the intervention was implemented.
Null hypothesis (H0): There were no statistically significant differences in vocabulary
retention, measured by the post-test score adjusted for the pre-test, between A2 students who
received spaced repetition and those who received traditional instruction.
MATERIALS AND METHODS
Research Focus
The study was conducted under a quantitative approach, as its purpose was to measure
the effect of spaced repetition on English vocabulary retention through numerical evidence
obtained before and after the intervention. This approach was appropriate because the research
sought to compare the performance of two groups, estimate changes in vocabulary retention, and
test hypotheses using descriptive and inferential statistical procedures (Mendoza et al., 2021). The
independent variable was the application of spaced repetition as a pedagogical strategy, while the
dependent variable was vocabulary retention in A2-level EFL students. Therefore, the
methodological structure was aligned with the need to determine whether systematic review at
planned intervals produced measurable differences in students’ lexical performance (Bruhn,
2021).
Type and design of research
The research followed a quasi-experimental pretest–post-test design with a non-
equivalent control group. This design was selected because the study was conducted in a real
school context, where random assignment of students was not feasible. For this reason, the
research worked with two intact class groups: one experimental group and one control group
(Alisoy & Sadigzade, 2025). Both groups were assessed before and after the intervention in order
to compare their vocabulary retention levels over time.
The experimental group received instruction supported by spaced repetition activities,
whereas the control group continued with the usual English teaching process without a systematic
review schedule. The pretest made it possible to identify the initial vocabulary level of both
groups, while the post-test allowed the study to estimate the changes observed after the six-week
intervention. This design was appropriate because it enabled the comparison of group
performance while statistically controlling for initial differences through covariance analysis
(Creswell, 2021).
Population and sample
The study was conducted at Unidad Educativa “18 de Octubre”, located in Portoviejo,
Manabí, Ecuador. The institution offers English as a foreign language at the secondary education
level, within a curricular structure aligned with the communicative goals established for public
education. The target population consisted of A2-level EFL students enrolled in secondary
education during the academic period in which the intervention was implemented.
Vol. 13/ Núm. 2 2026 pág. 2531
The sample consisted of 70 students aged between 13 and 15 years. A total intentional
non-probabilistic sampling procedure was used because the study was carried out with intact
classroom groups and random assignment was not feasible in the institutional context (Velazco
et al., 2022). Parallel A was assigned as the experimental group and included 35 students, whereas
Parallel B was assigned as the control group and included 35 students. Both groups shared similar
curricular conditions, school schedules, institutional resources, and English instruction time,
which allowed a methodologically acceptable comparison between them (Krippendorff, 2019).
Procedure and intervention
The procedure was organised in three sequential phases to ensure comparable conditions
between the experimental and control groups. In the first phase, during Week 1, the objective
vocabulary retention test and the Likert-type questionnaire were administered as pre-test
instruments to all participants. Both instruments were applied during regular English class hours,
under standardised instructions and similar classroom conditions.
In the second phase, from Week 2 to Week 7, the pedagogical intervention was
implemented with the experimental group. The intervention consisted of spaced repetition
activities focused on the same set of A2-level target vocabulary. Vocabulary review was
organised through planned intervals, following an operational sequence of 1, 3, 7, and 14 days,
adapted to the school timetable and classroom availability. Each session lasted approximately 40
minutes and was integrated into the regular English class. During the same period, the control
group continued with the usual English teaching process, without a systematic spaced repetition
schedule.
In the third phase, during Week 8, the same instruments were administered again as post-
test measures. The post-test application followed conditions equivalent to those of the pre-test to
reduce administration bias. This procedure allowed the study to compare changes between the
two groups and to estimate the effect of spaced repetition on vocabulary retention while
considering students’ initial performance.
Data collection techniques and instruments
Data collection was organised through two complementary techniques aligned with the
quantitative nature of the study and the operationalisation of the variables (Hinostroza et al.,
2025). The first technique corresponded to pedagogical assessment and was implemented through
an objective vocabulary retention test administered as both pre-test and post-test. This instrument
measured students’ lexical performance before and after the intervention, allowing the study to
estimate changes associated with spaced repetition over time. The test focused on the recognition,
identification, and contextual use of A2-level English vocabulary through structured items with
objective scoring criteria. The scores obtained made it possible to compare group performance
quantitatively and to apply inferential statistical analyses.
The sample consisted of 70 students aged between 13 and 15 years. A total intentional
non-probabilistic sampling procedure was used because the study was carried out with intact
classroom groups and random assignment was not feasible in the institutional context (Velazco
et al., 2022). Parallel A was assigned as the experimental group and included 35 students, whereas
Parallel B was assigned as the control group and included 35 students. Both groups shared similar
curricular conditions, school schedules, institutional resources, and English instruction time,
which allowed a methodologically acceptable comparison between them (Krippendorff, 2019).
Procedure and intervention
The procedure was organised in three sequential phases to ensure comparable conditions
between the experimental and control groups. In the first phase, during Week 1, the objective
vocabulary retention test and the Likert-type questionnaire were administered as pre-test
instruments to all participants. Both instruments were applied during regular English class hours,
under standardised instructions and similar classroom conditions.
In the second phase, from Week 2 to Week 7, the pedagogical intervention was
implemented with the experimental group. The intervention consisted of spaced repetition
activities focused on the same set of A2-level target vocabulary. Vocabulary review was
organised through planned intervals, following an operational sequence of 1, 3, 7, and 14 days,
adapted to the school timetable and classroom availability. Each session lasted approximately 40
minutes and was integrated into the regular English class. During the same period, the control
group continued with the usual English teaching process, without a systematic spaced repetition
schedule.
In the third phase, during Week 8, the same instruments were administered again as post-
test measures. The post-test application followed conditions equivalent to those of the pre-test to
reduce administration bias. This procedure allowed the study to compare changes between the
two groups and to estimate the effect of spaced repetition on vocabulary retention while
considering students’ initial performance.
Data collection techniques and instruments
Data collection was organised through two complementary techniques aligned with the
quantitative nature of the study and the operationalisation of the variables (Hinostroza et al.,
2025). The first technique corresponded to pedagogical assessment and was implemented through
an objective vocabulary retention test administered as both pre-test and post-test. This instrument
measured students’ lexical performance before and after the intervention, allowing the study to
estimate changes associated with spaced repetition over time. The test focused on the recognition,
identification, and contextual use of A2-level English vocabulary through structured items with
objective scoring criteria. The scores obtained made it possible to compare group performance
quantitatively and to apply inferential statistical analyses.
Vol. 13/ Núm. 2 2026 pág. 2532
The second technique corresponded to structured self-reporting and was applied through
a Likert-type questionnaire designed to examine students’ perceptions of spaced repetition,
vocabulary retention, and learning stability. The questionnaire explored subjective dimensions
related to memory reinforcement, repeated exposure to vocabulary, and perceived improvement
during the intervention process. Both instruments were administered to the 70 participants under
similar classroom conditions and during regular English lessons. The pre-test instruments were
applied before the intervention phase, whereas the post-test instruments were administered after
the completion of the six-week pedagogical process. This methodological organisation ensured
consistency between the variables studied, the instruments applied, and the statistical procedures
selected for the analysis (Masache-Escobar & Enciso, 2023).
Instrument 1: Objective vocabulary retention test (pre-test–post-test)
Instrument 1, corresponding to the objective vocabulary retention test in English level
A2, was designed according to content validity criteria (see table 1). The purpose was to ensure
that the items adequately assessed the proposed construction. The vocabulary was selected in
accordance with the content covered during the intervention period and the expected level of
linguistic competence for the participating students, in accordance with current curriculum
guidelines (Alisoy & Sadigzade, 2025).
The instrument was administered twice: first as a pre-test before the intervention and later
as a post-test after the six-week instructional process. In both applications, the scoring system
remained the same: each correct answer was assigned 1 point, while incorrect or blank answers
received 0 points. The total score ranged from 0 to 10 points, which allowed the results to be
interpreted both as raw scores and as percentages of vocabulary retention.
Table 1
Objective English Vocabulary Retention Test (Level A2)
English Vocabulary Retention Test – Level A2
Date: / /
Student Instructions
• Read each question and mark the correct answer.
• In the open-ended questions, write the meaning in Spanish.
Item
No. Item Type Question /
Statement
Option
A Option B Option C Option
D
Correct
Answer
1 Multiple
choice
What does
borrow
mean?
buy
borrow
(pedir
prestado)
sell pay B
2 Multiple
choice
What does
crowded
mean?
empty
full of
people
(lleno de
gente)
quiet closed B
3 Multiple
choice
What does
choose mean? run choose
(elegir) forget lose B
The second technique corresponded to structured self-reporting and was applied through
a Likert-type questionnaire designed to examine students’ perceptions of spaced repetition,
vocabulary retention, and learning stability. The questionnaire explored subjective dimensions
related to memory reinforcement, repeated exposure to vocabulary, and perceived improvement
during the intervention process. Both instruments were administered to the 70 participants under
similar classroom conditions and during regular English lessons. The pre-test instruments were
applied before the intervention phase, whereas the post-test instruments were administered after
the completion of the six-week pedagogical process. This methodological organisation ensured
consistency between the variables studied, the instruments applied, and the statistical procedures
selected for the analysis (Masache-Escobar & Enciso, 2023).
Instrument 1: Objective vocabulary retention test (pre-test–post-test)
Instrument 1, corresponding to the objective vocabulary retention test in English level
A2, was designed according to content validity criteria (see table 1). The purpose was to ensure
that the items adequately assessed the proposed construction. The vocabulary was selected in
accordance with the content covered during the intervention period and the expected level of
linguistic competence for the participating students, in accordance with current curriculum
guidelines (Alisoy & Sadigzade, 2025).
The instrument was administered twice: first as a pre-test before the intervention and later
as a post-test after the six-week instructional process. In both applications, the scoring system
remained the same: each correct answer was assigned 1 point, while incorrect or blank answers
received 0 points. The total score ranged from 0 to 10 points, which allowed the results to be
interpreted both as raw scores and as percentages of vocabulary retention.
Table 1
Objective English Vocabulary Retention Test (Level A2)
English Vocabulary Retention Test – Level A2
Date: / /
Student Instructions
• Read each question and mark the correct answer.
• In the open-ended questions, write the meaning in Spanish.
Item
No. Item Type Question /
Statement
Option
A Option B Option C Option
D
Correct
Answer
1 Multiple
choice
What does
borrow
mean?
buy
borrow
(pedir
prestado)
sell pay B
2 Multiple
choice
What does
crowded
mean?
empty
full of
people
(lleno de
gente)
quiet closed B
3 Multiple
choice
What does
choose mean? run choose
(elegir) forget lose B
Vol. 13/ Núm. 2 2026 pág. 2533
4 Multiple
choice
What does
expensive
mean?
cheap expensive
(caro) fast small B
5 Sentence
completion
I feel ___
because I
studied all
night.
hungry tired early easy B
6 Sentence
completion
This restaurant
is very ___.
The food costs
a lot.
cheap crowded expensive small C
7 Sentence
completion
She ___ the
bus at 7 a.m.
every day.
arrives takes chooses borrows B
8 Sentence
completion
Today it is
___. There are
many people
on the street.
quiet empty crowded late C
9 Short
answer
Write the
meaning of
neighborhood
in Spanish.
— — — — barrio
10 Short
answer
Write the
meaning of
healthy in
Spanish.
— — — — saludable
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca.
Scoring system (for Excel / Jamovi)
Correct answer = 1 point
Incorrect / blank = 0 points
Total, score = 0–10
The items included in the test focused on frequently used words in context, appropriate for
level A2, avoiding technical vocabulary or linguistic structures that exceeded the expected
competence of the students. This process sought to ensure that the answers reflected lexical
knowledge and not difficulties associated with the linguistic complexity of the instrument. The
suitability of the items was reviewed by English teachers with experience in secondary education,
who assessed the clarity, relevance and correspondence between the learning objectives and the
questions asked (Cajas & Cherres, 2024).
Given that the same instrument was used as a pre-test and post-test, the possible effect of
repeated testing, associated with the students' familiarity with the items, was considered. To
reduce this risk, methodological control measures were adopted. First, the order of presentation
of the items was modified in the second application, avoiding an identical sequence that could
favour answers from memory. Second, a sufficient time interval was established between the
4 Multiple
choice
What does
expensive
mean?
cheap expensive
(caro) fast small B
5 Sentence
completion
I feel ___
because I
studied all
night.
hungry tired early easy B
6 Sentence
completion
This restaurant
is very ___.
The food costs
a lot.
cheap crowded expensive small C
7 Sentence
completion
She ___ the
bus at 7 a.m.
every day.
arrives takes chooses borrows B
8 Sentence
completion
Today it is
___. There are
many people
on the street.
quiet empty crowded late C
9 Short
answer
Write the
meaning of
neighborhood
in Spanish.
— — — — barrio
10 Short
answer
Write the
meaning of
healthy in
Spanish.
— — — — saludable
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca.
Scoring system (for Excel / Jamovi)
Correct answer = 1 point
Incorrect / blank = 0 points
Total, score = 0–10
The items included in the test focused on frequently used words in context, appropriate for
level A2, avoiding technical vocabulary or linguistic structures that exceeded the expected
competence of the students. This process sought to ensure that the answers reflected lexical
knowledge and not difficulties associated with the linguistic complexity of the instrument. The
suitability of the items was reviewed by English teachers with experience in secondary education,
who assessed the clarity, relevance and correspondence between the learning objectives and the
questions asked (Cajas & Cherres, 2024).
Given that the same instrument was used as a pre-test and post-test, the possible effect of
repeated testing, associated with the students' familiarity with the items, was considered. To
reduce this risk, methodological control measures were adopted. First, the order of presentation
of the items was modified in the second application, avoiding an identical sequence that could
favour answers from memory. Second, a sufficient time interval was established between the
Vol. 13/ Núm. 2 2026 pág. 2534
pretest and posttest, corresponding to the total duration of the intervention, which reduced the
probability of immediate recall of the answers (Al-Khasawneh, 2023).
Likewise, the emphasis of the teaching process during the intervention was not on
memorising the items in the instrument, but rather on progressive vocabulary learning through
spaced repetition activities. This decision was made so that the changes observed in the post-test
would respond to lexical learning developed over time and not to mechanical repetition of the
test. These methodological considerations allowed us to conclude that Instrument 1 validly
assessed vocabulary retention and that the differences observed between the pre-test and post-test
were not attributable to familiarity with the test, but rather to the teaching process implemented
during the study.
Instrument 2: Likert scale questionnaire
Instrument 2, corresponding to the Likert scale questionnaire, was designed to gather
students' perceptions of spaced repetition, vocabulary retention, and the learning process
experienced during the intervention (see table 2). Given that the population consisted of A2-level
English learners aged between 13 and 15, linguistic comprehension was explicitly considered a
central criterion in the administration of the instrument (Teng, 2023).
The questionnaire was administered twice, following the same temporal sequence as the
objective vocabulary test. The first application was conducted before the intervention to identify
students’ initial perceptions of vocabulary learning, memory stability, and review practices. The
second application was conducted after the six-week intervention to examine whether students’
perceptions changed after the spaced repetition activities. This double application made it possible
to compare perceived learning conditions before and after the pedagogical process.
Table 2
Questionnaire with Likert-type scale on spaced repetition and lexical learning
Item
No. Variable Statement 1 2 3 4 5
RE1 Spaced Repetition Vocabulary was reviewed at
different times during the course. ☐ ☐ ☐ ☐ ☐
RE2 Spaced Repetition Words appeared again in later
activities. ☐ ☐ ☐ ☐ ☐
RE3 Spaced Repetition Vocabulary practice was spread
across several lessons. ☐ ☐ ☐ ☐ ☐
RE4 Spaced Repetition Time between reviews helped me
remember words better. ☐ ☐ ☐ ☐ ☐
RE5 Spaced Repetition Reviewing vocabulary over time
reduced forgetting. ☐ ☐ ☐ ☐ ☐
RV1 Vocabulary Retention
(Perceived)
I remembered the meaning of words
learned earlier. ☐ ☐ ☐ ☐ ☐
RV2 Vocabulary Retention
(Perceived)
I recognized vocabulary studied in
previous weeks. ☐ ☐ ☐ ☐ ☐
pretest and posttest, corresponding to the total duration of the intervention, which reduced the
probability of immediate recall of the answers (Al-Khasawneh, 2023).
Likewise, the emphasis of the teaching process during the intervention was not on
memorising the items in the instrument, but rather on progressive vocabulary learning through
spaced repetition activities. This decision was made so that the changes observed in the post-test
would respond to lexical learning developed over time and not to mechanical repetition of the
test. These methodological considerations allowed us to conclude that Instrument 1 validly
assessed vocabulary retention and that the differences observed between the pre-test and post-test
were not attributable to familiarity with the test, but rather to the teaching process implemented
during the study.
Instrument 2: Likert scale questionnaire
Instrument 2, corresponding to the Likert scale questionnaire, was designed to gather
students' perceptions of spaced repetition, vocabulary retention, and the learning process
experienced during the intervention (see table 2). Given that the population consisted of A2-level
English learners aged between 13 and 15, linguistic comprehension was explicitly considered a
central criterion in the administration of the instrument (Teng, 2023).
The questionnaire was administered twice, following the same temporal sequence as the
objective vocabulary test. The first application was conducted before the intervention to identify
students’ initial perceptions of vocabulary learning, memory stability, and review practices. The
second application was conducted after the six-week intervention to examine whether students’
perceptions changed after the spaced repetition activities. This double application made it possible
to compare perceived learning conditions before and after the pedagogical process.
Table 2
Questionnaire with Likert-type scale on spaced repetition and lexical learning
Item
No. Variable Statement 1 2 3 4 5
RE1 Spaced Repetition Vocabulary was reviewed at
different times during the course. ☐ ☐ ☐ ☐ ☐
RE2 Spaced Repetition Words appeared again in later
activities. ☐ ☐ ☐ ☐ ☐
RE3 Spaced Repetition Vocabulary practice was spread
across several lessons. ☐ ☐ ☐ ☐ ☐
RE4 Spaced Repetition Time between reviews helped me
remember words better. ☐ ☐ ☐ ☐ ☐
RE5 Spaced Repetition Reviewing vocabulary over time
reduced forgetting. ☐ ☐ ☐ ☐ ☐
RV1 Vocabulary Retention
(Perceived)
I remembered the meaning of words
learned earlier. ☐ ☐ ☐ ☐ ☐
RV2 Vocabulary Retention
(Perceived)
I recognized vocabulary studied in
previous weeks. ☐ ☐ ☐ ☐ ☐
Vol. 13/ Núm. 2 2026 pág. 2535
RV3 Vocabulary Retention
(Perceived)
I could recall words without
reviewing immediately before. ☐ ☐ ☐ ☐ ☐
RV4 Vocabulary Retention
(Perceived)
Vocabulary stayed in my memory
during the study period. ☐ ☐ ☐ ☐ ☐
RV5 Vocabulary Retention
(Perceived)
I felt my vocabulary knowledge was
stable over time. ☐ ☐ ☐ ☐ ☐
PA1 Learning Perception I felt more confident when
remembering English words. ☐ ☐ ☐ ☐ ☐
PA2 Learning Perception I noticed less vocabulary loss over
time. ☐ ☐ ☐ ☐ ☐
PA3 Learning Perception Vocabulary learning felt more
consistent. ☐ ☐ ☐ ☐ ☐
PA4 Learning Perception Spaced review was helpful for
learning vocabulary. ☐ ☐ ☐ ☐ ☐
PA5 Learning Perception My overall vocabulary performance
improved. ☐ ☐ ☐ ☐ ☐
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca.
The instrument was administered to all 70 students, both in the experimental group and
the control group, maintaining the same structure and number of items at both times. The
questionnaire had 5 answer options, from 1 the lowest value to 5 the highest. To ensure that the
responses reflected real perceptions and not difficulties in interpretation, the questionnaire was
administered in Spanish, using clear and accessible language for the participants. This
methodological decision sought to reduce biases associated with limited understanding of the
foreign language and to protect the validity of the data collected, especially in self-report scales,
where semantic clarity is decisive for the quality of the responses (Cabrera-Solano et al., 2023).
The items were formulated to describe specific classroom experiences, avoiding
ambiguous structures or technical vocabulary that could lead to divergent interpretations. Before
their final application, the statements were reviewed by English teachers, who assessed their
clarity, coherence and suitability for the educational context, thus helping to strengthen the
validity of the instrument from a pedagogical perspective (Lee et al., 2021; Li, 2025; Zhang et al.,
2022).
Reliability Analysis
The reliability of Instrument 2, corresponding to the questionnaire with a Likert scale,
was examined using McDonald's omega coefficient (ω) and Cronbach's alpha coefficient (α). The
coefficients were applied independently in the pre-test and post-test stages, after the execution of
a pilot test (see table 3). This procedure allowed estimating the internal consistency of the items
that made up each scale, considering current psychometric criteria in educational research (Pánek,
2022).
RV3 Vocabulary Retention
(Perceived)
I could recall words without
reviewing immediately before. ☐ ☐ ☐ ☐ ☐
RV4 Vocabulary Retention
(Perceived)
Vocabulary stayed in my memory
during the study period. ☐ ☐ ☐ ☐ ☐
RV5 Vocabulary Retention
(Perceived)
I felt my vocabulary knowledge was
stable over time. ☐ ☐ ☐ ☐ ☐
PA1 Learning Perception I felt more confident when
remembering English words. ☐ ☐ ☐ ☐ ☐
PA2 Learning Perception I noticed less vocabulary loss over
time. ☐ ☐ ☐ ☐ ☐
PA3 Learning Perception Vocabulary learning felt more
consistent. ☐ ☐ ☐ ☐ ☐
PA4 Learning Perception Spaced review was helpful for
learning vocabulary. ☐ ☐ ☐ ☐ ☐
PA5 Learning Perception My overall vocabulary performance
improved. ☐ ☐ ☐ ☐ ☐
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca.
The instrument was administered to all 70 students, both in the experimental group and
the control group, maintaining the same structure and number of items at both times. The
questionnaire had 5 answer options, from 1 the lowest value to 5 the highest. To ensure that the
responses reflected real perceptions and not difficulties in interpretation, the questionnaire was
administered in Spanish, using clear and accessible language for the participants. This
methodological decision sought to reduce biases associated with limited understanding of the
foreign language and to protect the validity of the data collected, especially in self-report scales,
where semantic clarity is decisive for the quality of the responses (Cabrera-Solano et al., 2023).
The items were formulated to describe specific classroom experiences, avoiding
ambiguous structures or technical vocabulary that could lead to divergent interpretations. Before
their final application, the statements were reviewed by English teachers, who assessed their
clarity, coherence and suitability for the educational context, thus helping to strengthen the
validity of the instrument from a pedagogical perspective (Lee et al., 2021; Li, 2025; Zhang et al.,
2022).
Reliability Analysis
The reliability of Instrument 2, corresponding to the questionnaire with a Likert scale,
was examined using McDonald's omega coefficient (ω) and Cronbach's alpha coefficient (α). The
coefficients were applied independently in the pre-test and post-test stages, after the execution of
a pilot test (see table 3). This procedure allowed estimating the internal consistency of the items
that made up each scale, considering current psychometric criteria in educational research (Pánek,
2022).
Vol. 13/ Núm. 2 2026 pág. 2536
Table 3
Reliability coefficients (McDonald's ω and Cronbach's α) of the pre-test and post-test Likert
questionnaire
Instrument Moment Scale Reliability
ω α
Likert Pretest RE 0.774 0.779
Likert Pretest RV 0.814 0.808
Likert Pretest PA 0.736 0.729
Likert Postest RE 0.861 0.859
Likert Postest RV 0.801 0.8
Likert Postest PA 0.874 0.872
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The reliability analysis was conducted to determine the internal consistency of the Likert-
type questionnaire in both applications (Creswell, 2021). McDonald’s omega coefficient (ω) was
used as the main reliability estimate because it is suitable for scales whose items may not
contribute equally to the construct measured (Zou & Xu, 2023). Cronbach’s alpha coefficient (α)
was also reported as a complementary indicator due to its frequent use in educational research.
Both coefficients were calculated separately for the three questionnaire scales: spaced repetition
(SR), perceived vocabulary retention (VR), and learning perception (LP).
In the pre-test phase, the reliability coefficients showed acceptable internal consistency
across the three questionnaire scales. The spaced repetition scale obtained ω = 0.774 and α =
0.779, indicating adequate consistency among its items. The perceived vocabulary retention scale
presented ω = 0.814 and α = 0.808, which reflected a stronger level of internal consistency. The
learning perception scale obtained ω = 0.736 and α = 0.729, values that were also acceptable for
educational research and supported the use of the scale in the initial measurement.
In the post-test phase, the coefficients remained within acceptable and high reliability
ranges. The spaced repetition scale increased to ω = 0.861 and α = 0.859, while the perceived
vocabulary retention scale obtained ω = 0.801 and α = 0.800. The learning perception scale
presented the highest internal consistency, with ω = 0.874 and α = 0.872. These results indicated
that the Likert-type questionnaire maintained a stable internal structure in both applications and
supported its use as a complementary instrument for interpreting students’ perceptions of
vocabulary learning and spaced repetition.
Results analysis technique
Jamovi software version 2.7.17 was used for the quantitative analysis of the data. The
information obtained from the objective vocabulary test and the Likert-type questionnaire was
first organised in an Excel database and then imported into Jamovi for statistical processing.
Descriptive statistics were calculated to summarise the pre-test and post-test scores of both
Table 3
Reliability coefficients (McDonald's ω and Cronbach's α) of the pre-test and post-test Likert
questionnaire
Instrument Moment Scale Reliability
ω α
Likert Pretest RE 0.774 0.779
Likert Pretest RV 0.814 0.808
Likert Pretest PA 0.736 0.729
Likert Postest RE 0.861 0.859
Likert Postest RV 0.801 0.8
Likert Postest PA 0.874 0.872
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The reliability analysis was conducted to determine the internal consistency of the Likert-
type questionnaire in both applications (Creswell, 2021). McDonald’s omega coefficient (ω) was
used as the main reliability estimate because it is suitable for scales whose items may not
contribute equally to the construct measured (Zou & Xu, 2023). Cronbach’s alpha coefficient (α)
was also reported as a complementary indicator due to its frequent use in educational research.
Both coefficients were calculated separately for the three questionnaire scales: spaced repetition
(SR), perceived vocabulary retention (VR), and learning perception (LP).
In the pre-test phase, the reliability coefficients showed acceptable internal consistency
across the three questionnaire scales. The spaced repetition scale obtained ω = 0.774 and α =
0.779, indicating adequate consistency among its items. The perceived vocabulary retention scale
presented ω = 0.814 and α = 0.808, which reflected a stronger level of internal consistency. The
learning perception scale obtained ω = 0.736 and α = 0.729, values that were also acceptable for
educational research and supported the use of the scale in the initial measurement.
In the post-test phase, the coefficients remained within acceptable and high reliability
ranges. The spaced repetition scale increased to ω = 0.861 and α = 0.859, while the perceived
vocabulary retention scale obtained ω = 0.801 and α = 0.800. The learning perception scale
presented the highest internal consistency, with ω = 0.874 and α = 0.872. These results indicated
that the Likert-type questionnaire maintained a stable internal structure in both applications and
supported its use as a complementary instrument for interpreting students’ perceptions of
vocabulary learning and spaced repetition.
Results analysis technique
Jamovi software version 2.7.17 was used for the quantitative analysis of the data. The
information obtained from the objective vocabulary test and the Likert-type questionnaire was
first organised in an Excel database and then imported into Jamovi for statistical processing.
Descriptive statistics were calculated to summarise the pre-test and post-test scores of both
Vol. 13/ Núm. 2 2026 pág. 2537
groups, including means, standard deviations, minimum values, and maximum values. Reliability
analysis was performed for the Likert-type questionnaire using McDonald’s omega and
Cronbach’s alpha coefficients. Subsequently, inferential analyses were conducted to compare the
initial performance of the control and experimental groups and to estimate the effect of spaced
repetition on vocabulary retention. The main inferential procedure was analysis of covariance
(ANCOVA), with the post-test vocabulary score as the dependent variable, group as the fixed
factor, and pre-test vocabulary score as the covariate.
Ethical safeguards were applied throughout the study. The data were coded to protect the
identity of the students and to ensure confidentiality during statistical processing. Participation
was handled within the institutional framework of the educational unit, and the information was
used only for academic and research purposes. In addition, the study followed general principles
of research integrity, including responsible data management, absence of declared conflicts of
interest, and respect for the privacy and rights of the participants (COPE, 2024).
Normality analysis
Normality was examined before applying the inferential procedures. The Shapiro–Wilk
test was used for the pre-test and post-test vocabulary scores, and its results were complemented
with the inspection of distribution plots and Q–Q plots (Samoilenko & Osei, 2021). Descriptive
indicators of skewness and kurtosis were also reviewed to support the interpretation of the data
distribution. Given the sample size and the use of linear modelling procedures, the decision was
not based exclusively on the p-value, but on the joint evaluation of statistical and graphical
evidence (Umesh & Dubey, 2022).
Covariance analysis
Before proceeding with the covariance analysis, the statistical assumptions associated
with this model were verified to ensure the validity of the inferences made. This control was
particularly relevant given the quasi-experimental nature of the study and the use of non-
equivalent groups. Furthermore, it is relevant due to the usual situation in educational research
carried out in real classroom contexts (Samoilenko & Osei, 2021). First, the relationship between
the covariate and the dependent variable was examined. The purpose of this was to confirm a
pattern compatible with linearity. Graphical inspection and preliminary analysis indicated an
adequate relationship between the pretest and posttest vocabulary retention scores, a necessary
condition for the application of ANCOVA (Hadi et al., 2023).
Subsequently, the homogeneity of regression slopes was examined by analysing the
interaction between the study group and the covariate. This step made it possible to determine
whether the relationship between the pre-test and post-test vocabulary scores differed between
the control and experimental groups. The verification of this assumption was relevant because a
significant interaction would indicate that the effect of the intervention varied according to
students’ initial vocabulary level (Creswell, 2021). Similarly, homoscedasticity was checked by
groups, including means, standard deviations, minimum values, and maximum values. Reliability
analysis was performed for the Likert-type questionnaire using McDonald’s omega and
Cronbach’s alpha coefficients. Subsequently, inferential analyses were conducted to compare the
initial performance of the control and experimental groups and to estimate the effect of spaced
repetition on vocabulary retention. The main inferential procedure was analysis of covariance
(ANCOVA), with the post-test vocabulary score as the dependent variable, group as the fixed
factor, and pre-test vocabulary score as the covariate.
Ethical safeguards were applied throughout the study. The data were coded to protect the
identity of the students and to ensure confidentiality during statistical processing. Participation
was handled within the institutional framework of the educational unit, and the information was
used only for academic and research purposes. In addition, the study followed general principles
of research integrity, including responsible data management, absence of declared conflicts of
interest, and respect for the privacy and rights of the participants (COPE, 2024).
Normality analysis
Normality was examined before applying the inferential procedures. The Shapiro–Wilk
test was used for the pre-test and post-test vocabulary scores, and its results were complemented
with the inspection of distribution plots and Q–Q plots (Samoilenko & Osei, 2021). Descriptive
indicators of skewness and kurtosis were also reviewed to support the interpretation of the data
distribution. Given the sample size and the use of linear modelling procedures, the decision was
not based exclusively on the p-value, but on the joint evaluation of statistical and graphical
evidence (Umesh & Dubey, 2022).
Covariance analysis
Before proceeding with the covariance analysis, the statistical assumptions associated
with this model were verified to ensure the validity of the inferences made. This control was
particularly relevant given the quasi-experimental nature of the study and the use of non-
equivalent groups. Furthermore, it is relevant due to the usual situation in educational research
carried out in real classroom contexts (Samoilenko & Osei, 2021). First, the relationship between
the covariate and the dependent variable was examined. The purpose of this was to confirm a
pattern compatible with linearity. Graphical inspection and preliminary analysis indicated an
adequate relationship between the pretest and posttest vocabulary retention scores, a necessary
condition for the application of ANCOVA (Hadi et al., 2023).
Subsequently, the homogeneity of regression slopes was examined by analysing the
interaction between the study group and the covariate. This step made it possible to determine
whether the relationship between the pre-test and post-test vocabulary scores differed between
the control and experimental groups. The verification of this assumption was relevant because a
significant interaction would indicate that the effect of the intervention varied according to
students’ initial vocabulary level (Creswell, 2021). Similarly, homoscedasticity was checked by
Vol. 13/ Núm. 2 2026 pág. 2538
approximating the equality of post-test variances between groups. This analysis was based on
tests of equality of variances and inspection of the dispersion of residuals, which allowed us to
rule out relevant patterns of heterogeneity (Hernández & Mendoza, 2018).
The distribution of the model residuals was examined to identify severe deviations from
the assumption of normality. Graphical evaluation using Q-Q plots and descriptive statistics did
not reveal any irregularities that would compromise the robustness of the analysis. The
independence of the observations was assumed based on the study design and the individual
application of the data collection instruments (Sordi, 2021). Verification of these assumptions
supported the use of covariance analysis as an appropriate statistical procedure for estimating the
effect of spaced repetition on vocabulary retention, controlling for the students' initial
performance.
RESULTS AND DISCUSSION
The initial values showed proximity between groups (see Table 4). The dispersion was
similar. The starting point was comparable. This scenario reduced the risk of prior biases. The
methodological reading was clear. Subsequent differences could not be attributed to initial
advantages. This condition strengthened the adjusted causal inference envisaged in the design
(Samoilenko & Osei, 2021).
Table 4
Descriptive statistics of the vocabulary retention pretest by group
Descriptive
Group Pretest
N Control 35
Experimental 35
Media Control 4.74
Experimental 4.97
Standard deviation Control 0.741
Experimental 0.822
Minimum Control 4
Experimental 4
Maximum Control 6
Experimental 6
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The descriptive pattern changed clearly. The separation between groups widened. The
experimental group showed a higher level (see Table 5). Visual contrast suggested an effect
associated with the intervention. This evidence justified the use of an adjusted model to estimate
the net impact, considering previous performance (Alisoy & Sadigzade, 2025).
approximating the equality of post-test variances between groups. This analysis was based on
tests of equality of variances and inspection of the dispersion of residuals, which allowed us to
rule out relevant patterns of heterogeneity (Hernández & Mendoza, 2018).
The distribution of the model residuals was examined to identify severe deviations from
the assumption of normality. Graphical evaluation using Q-Q plots and descriptive statistics did
not reveal any irregularities that would compromise the robustness of the analysis. The
independence of the observations was assumed based on the study design and the individual
application of the data collection instruments (Sordi, 2021). Verification of these assumptions
supported the use of covariance analysis as an appropriate statistical procedure for estimating the
effect of spaced repetition on vocabulary retention, controlling for the students' initial
performance.
RESULTS AND DISCUSSION
The initial values showed proximity between groups (see Table 4). The dispersion was
similar. The starting point was comparable. This scenario reduced the risk of prior biases. The
methodological reading was clear. Subsequent differences could not be attributed to initial
advantages. This condition strengthened the adjusted causal inference envisaged in the design
(Samoilenko & Osei, 2021).
Table 4
Descriptive statistics of the vocabulary retention pretest by group
Descriptive
Group Pretest
N Control 35
Experimental 35
Media Control 4.74
Experimental 4.97
Standard deviation Control 0.741
Experimental 0.822
Minimum Control 4
Experimental 4
Maximum Control 6
Experimental 6
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The descriptive pattern changed clearly. The separation between groups widened. The
experimental group showed a higher level (see Table 5). Visual contrast suggested an effect
associated with the intervention. This evidence justified the use of an adjusted model to estimate
the net impact, considering previous performance (Alisoy & Sadigzade, 2025).
Vol. 13/ Núm. 2 2026 pág. 2539
Table 5
Descriptive statistics of the post-test of vocabulary retention by group
Descriptive
Group Postest
N Control 35
Experimental 35
Media Control 5.57
Experimental 8.03
Standard deviation Control 0.502
Experimental 0.822
Minimum Control 5
Experimental 7
Maximum Control 6
Experimental 9
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The descriptive pattern changed clearly after the intervention. In raw-score terms, the
control group increased from 4.74 to 5.57 points, whereas the experimental group increased from
4.97 to 8.03 points (see Table 5). Because the vocabulary test had a maximum score of 10 points,
these values also indicated that the control group moved from 47.4% to 55.7%, while the
experimental group moved from 49.7% to 80.3%. This descriptive percentage reading does not
replace the inferential analysis; rather, it provides a pedagogical interpretation of the magnitude
of change observed before applying the adjusted statistical model (Namaziandost et al., 2023).
Table 6
t-Test for independent samples of the vocabulary retention pre-test
t-Test for Independent Samples
Confidence
Interval al 95%
Statistical gl p Effect
Size Bottom Upper
Pretest T the
Student -1.22 68.0 .226 Cohen's
d -0.292 -0.762 0.180
Note. Hₐ μControl ≠ μExperimental
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The initial variability was distributed in a comparable manner (see Table 7). The case was
considered satisfied. This fact reinforced the stability of the previous contrast. It also reduced the
Table 5
Descriptive statistics of the post-test of vocabulary retention by group
Descriptive
Group Postest
N Control 35
Experimental 35
Media Control 5.57
Experimental 8.03
Standard deviation Control 0.502
Experimental 0.822
Minimum Control 5
Experimental 7
Maximum Control 6
Experimental 9
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The descriptive pattern changed clearly after the intervention. In raw-score terms, the
control group increased from 4.74 to 5.57 points, whereas the experimental group increased from
4.97 to 8.03 points (see Table 5). Because the vocabulary test had a maximum score of 10 points,
these values also indicated that the control group moved from 47.4% to 55.7%, while the
experimental group moved from 49.7% to 80.3%. This descriptive percentage reading does not
replace the inferential analysis; rather, it provides a pedagogical interpretation of the magnitude
of change observed before applying the adjusted statistical model (Namaziandost et al., 2023).
Table 6
t-Test for independent samples of the vocabulary retention pre-test
t-Test for Independent Samples
Confidence
Interval al 95%
Statistical gl p Effect
Size Bottom Upper
Pretest T the
Student -1.22 68.0 .226 Cohen's
d -0.292 -0.762 0.180
Note. Hₐ μControl ≠ μExperimental
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The initial variability was distributed in a comparable manner (see Table 7). The case was
considered satisfied. This fact reinforced the stability of the previous contrast. It also reduced the
Vol. 13/ Núm. 2 2026 pág. 2540
chance of distortion from uneven spread. The initial comparison was methodologically
safeguarded (Acosta et al., 2022).
Table 7
Homogeneity test
Levene test for homogeneity of variances
F gl gl2 p
Pretest 0.0861 1 68 .770
Note. A low p-value suggests a violation of the equal variance assumption
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The pretest acted as a predictor of final performance (see Table 8). Statistical control was
relevant. Significant interaction indicated a conditioned effect. The intervention did not operate
uniformly. The impact varied according to the initial level; therefore, this reading provided a
differentiated interpretation of the treatment. The model captured that complexity without
simplifying it (Zhang, 2025).
Table 8
Results of the analysis of covariance (ANCOVA) for the vocabulary retention post-test
ANCOVA - Postest
Sum of
Squares gl Mean Square F p
Group 0.115 1 0.1149 2.01 .161
Pretest 24.925 1 24.9246 435.93 <.001
Group ✻
Pretest 1.355 1 1.3550 23.70 <.001
Residuals 3.774 66 0.0572
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The homogeneity of variances was not fully maintained (see Table 9). The result called
for caution as balanced sample sizes mitigated risk. The methodological literature admitted this
condition in applied contexts. The interpretation remained prudent and limited (Lee et al., 2021).
Table 9
Verification of ANCOVA assumptions
Levene test for homogeneity of variances
F gl1 gl2 p
9.27 1 68 .003
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The test indicated statistical deviation (see Table 10). The criterion was not based on the
p-value alone. The evaluation considered the robustness of the model. The decision integrated
chance of distortion from uneven spread. The initial comparison was methodologically
safeguarded (Acosta et al., 2022).
Table 7
Homogeneity test
Levene test for homogeneity of variances
F gl gl2 p
Pretest 0.0861 1 68 .770
Note. A low p-value suggests a violation of the equal variance assumption
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The pretest acted as a predictor of final performance (see Table 8). Statistical control was
relevant. Significant interaction indicated a conditioned effect. The intervention did not operate
uniformly. The impact varied according to the initial level; therefore, this reading provided a
differentiated interpretation of the treatment. The model captured that complexity without
simplifying it (Zhang, 2025).
Table 8
Results of the analysis of covariance (ANCOVA) for the vocabulary retention post-test
ANCOVA - Postest
Sum of
Squares gl Mean Square F p
Group 0.115 1 0.1149 2.01 .161
Pretest 24.925 1 24.9246 435.93 <.001
Group ✻
Pretest 1.355 1 1.3550 23.70 <.001
Residuals 3.774 66 0.0572
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The homogeneity of variances was not fully maintained (see Table 9). The result called
for caution as balanced sample sizes mitigated risk. The methodological literature admitted this
condition in applied contexts. The interpretation remained prudent and limited (Lee et al., 2021).
Table 9
Verification of ANCOVA assumptions
Levene test for homogeneity of variances
F gl1 gl2 p
9.27 1 68 .003
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The test indicated statistical deviation (see Table 10). The criterion was not based on the
p-value alone. The evaluation considered the robustness of the model. The decision integrated
Vol. 13/ Núm. 2 2026 pág. 2541
complementary evidence. This approach was consistent with current practices in educational
analysis (Al-Khasawneh, 2023).
Table 10
Normality Test (Shapiro-Wilk)
Normality Test (Shapiro-Wilk)
Statistical p
0.772 <.001
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
Visual inspection of the Q–Q Graph of the standardized residuals of the ANCOVA model
showed reasonable alignment (see Figure 1). No critical extremes were observed. The pattern
supported the stability of the model. Graphic evidence complemented the formal contrasts. The
joint reading made it possible to sustain the operational validity of the adjustment (Esquivel-
Gámez & Berthely-Barrios, 2025).
Figure 1
Q–Q graph of the standardized residuals of the ANCOVA model
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The results of the study allowed us to analyse spaced repetition as a pedagogical strategy
conditioned by the initial level of the students. The improvement in vocabulary retention was not
uniform. The observed effect depended on the lexical starting point. This pattern coincided with
cognitive models that described learning as a process sensitive to repeated memory activation and
the prior stability of lexical representations (Teng, 2023). The significant interaction between the
group and the pretest revealed that spaced repetition modulated learning differentially. Students
did not respond homogeneously to the treatment, as the impact varied depending on the degree of
initial vocabulary consolidation. This interpretation was consistent with research indicating that
complementary evidence. This approach was consistent with current practices in educational
analysis (Al-Khasawneh, 2023).
Table 10
Normality Test (Shapiro-Wilk)
Normality Test (Shapiro-Wilk)
Statistical p
0.772 <.001
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
Visual inspection of the Q–Q Graph of the standardized residuals of the ANCOVA model
showed reasonable alignment (see Figure 1). No critical extremes were observed. The pattern
supported the stability of the model. Graphic evidence complemented the formal contrasts. The
joint reading made it possible to sustain the operational validity of the adjustment (Esquivel-
Gámez & Berthely-Barrios, 2025).
Figure 1
Q–Q graph of the standardized residuals of the ANCOVA model
Source: Elaborated by Gorozabel Monge, Molina Pinargote, López López, and Bonilla Tenesaca based on data
processed in Jamovi 2.7.17.
The results of the study allowed us to analyse spaced repetition as a pedagogical strategy
conditioned by the initial level of the students. The improvement in vocabulary retention was not
uniform. The observed effect depended on the lexical starting point. This pattern coincided with
cognitive models that described learning as a process sensitive to repeated memory activation and
the prior stability of lexical representations (Teng, 2023). The significant interaction between the
group and the pretest revealed that spaced repetition modulated learning differentially. Students
did not respond homogeneously to the treatment, as the impact varied depending on the degree of
initial vocabulary consolidation. This interpretation was consistent with research indicating that
Vol. 13/ Núm. 2 2026 pág. 2542
the effectiveness of distributed review depends on the prior state of the memory trace (Salgado et
al., 2019).
From this perspective, spaced repetition did not operate as a neutral application technique;
rather, its effectiveness was mediated by the initial conditions of learning. It functioned as an
adaptive mechanism. Its effect adjusted to individual differences. This behaviour was described
in previous studies in foreign language teaching, where the timing of reviews was more effective
when it considered the student's learning trajectory (Alhazmi, 2024).
The improvement in the experimental group also demonstrated immediate repetition as
the dominant practice in vocabulary teaching. The literature pointed out that initial exposure,
without planned revisions, produces fragile and short-lived learning. In contrast, the temporal
distribution of reviews favoured active retrieval and stabilisation of memory, even with limited
instructional time (Wang & Lee, 2021). In the Latin American context, these findings took on a
particular nuance. Several regional studies highlighted the limited number of hours and scarce
exposure to English outside the classroom. Under these conditions, spaced repetition emerged as
a viable strategy that did not require expanding content or increasing hours but rather reorganising
the use of available time (Masache-Escobar & Enciso, 2023; Namaziandost et al., 2020).
In most cases, students depended on the school environment for their English learning
and practice, so the lack of extracurricular practice limited opportunities for spontaneous
vocabulary recovery. In other words, the deliberate planning of distributed revisions acted as a
compensatory mechanism for natural exposure, offering multiple opportunities for lexical
reactivation within the classroom. The results of the Likert-type questionnaire complemented this
interpretation. The trends observed in the scales suggested greater internal consistency in students'
perceptions after the intervention. The results were consistent with studies indicating that
perceptions of learning improve when forgetting is reduced and recall becomes more stable over
time (Alisoy & Sadigzade, 2025). The convergence between performance data and perceptions
provided methodological triangulation that strengthened the validity of the overall interpretation.
From a methodological standpoint, the significant interaction justified the use of a model
with explicit interaction. This approach avoided simplistic interpretations of the treatment effect.
Modelling individual variability was consistent with recent recommendations emphasising the
need to capture the complexity of learning in applied educational studies (Cajas & Cherres, 2024;
Vargas-Saritama & Celi, 2024). Spaced repetition was not configured as a universal solution. It
behaved as an effective strategy under specific conditions. Its value lay in time management and
repeated memory activation. This reading was aligned with cognitive principles of learning and
the structural limitations of educational contexts with restricted resources.
the effectiveness of distributed review depends on the prior state of the memory trace (Salgado et
al., 2019).
From this perspective, spaced repetition did not operate as a neutral application technique;
rather, its effectiveness was mediated by the initial conditions of learning. It functioned as an
adaptive mechanism. Its effect adjusted to individual differences. This behaviour was described
in previous studies in foreign language teaching, where the timing of reviews was more effective
when it considered the student's learning trajectory (Alhazmi, 2024).
The improvement in the experimental group also demonstrated immediate repetition as
the dominant practice in vocabulary teaching. The literature pointed out that initial exposure,
without planned revisions, produces fragile and short-lived learning. In contrast, the temporal
distribution of reviews favoured active retrieval and stabilisation of memory, even with limited
instructional time (Wang & Lee, 2021). In the Latin American context, these findings took on a
particular nuance. Several regional studies highlighted the limited number of hours and scarce
exposure to English outside the classroom. Under these conditions, spaced repetition emerged as
a viable strategy that did not require expanding content or increasing hours but rather reorganising
the use of available time (Masache-Escobar & Enciso, 2023; Namaziandost et al., 2020).
In most cases, students depended on the school environment for their English learning
and practice, so the lack of extracurricular practice limited opportunities for spontaneous
vocabulary recovery. In other words, the deliberate planning of distributed revisions acted as a
compensatory mechanism for natural exposure, offering multiple opportunities for lexical
reactivation within the classroom. The results of the Likert-type questionnaire complemented this
interpretation. The trends observed in the scales suggested greater internal consistency in students'
perceptions after the intervention. The results were consistent with studies indicating that
perceptions of learning improve when forgetting is reduced and recall becomes more stable over
time (Alisoy & Sadigzade, 2025). The convergence between performance data and perceptions
provided methodological triangulation that strengthened the validity of the overall interpretation.
From a methodological standpoint, the significant interaction justified the use of a model
with explicit interaction. This approach avoided simplistic interpretations of the treatment effect.
Modelling individual variability was consistent with recent recommendations emphasising the
need to capture the complexity of learning in applied educational studies (Cajas & Cherres, 2024;
Vargas-Saritama & Celi, 2024). Spaced repetition was not configured as a universal solution. It
behaved as an effective strategy under specific conditions. Its value lay in time management and
repeated memory activation. This reading was aligned with cognitive principles of learning and
the structural limitations of educational contexts with restricted resources.
Vol. 13/ Núm. 2 2026 pág. 2543
CONCLUSIONS
The study aimed to determine the efficiency of spaced repetition in vocabulary retention
among A2-level English learners. The results showed a significant improvement in the
performance of the group that received the intervention, once the initial level of lexical knowledge
had been controlled for. This evidence provided a direct response to the objective set and
confirmed the relevance of the quantitative approach adopted. The descriptive analysis revealed
significant and similar data between the two study groups (Teng, 2023). After the intervention
was applied, the experimental group achieved a higher level of lexical retention. Therefore, the
temporal organisation of revisions has a significant influence on the process of teaching and
learning the English language. On the other hand, it can be determined that memory stability is
linked to retrieval distributed over time (Alisoy & Sadigzade, 2025; Lee et al., 2021).
The covariance model confirmed that prior performance acted as a predictor of final
performance. Furthermore, the significant interaction between the group and the pretest indicated
that the efficiency of spaced repetition depended on the student's initial level. The treatment did
not produce a uniform effect. This condition provided a more accurate interpretation of the
phenomenon and avoided simplistic interpretations of the impact of the strategy applied
(Alhazmi, 2024).
The study found significant improvements in vocabulary retention after the intervention
to address the objectives. Additionally, the viability of spaced repetition-based activities in an
educational context was confirmed. The experimental group's pre-test and post-test results also
showed statistically significant differences. As a result, these findings validate the study's internal
consistency and the applicability of the tools employed. The null hypothesis, which proposed that
there were no differences in vocabulary retention between groups, was rejected considering the
empirical findings. After controlling for the initial level assessed in the pre-test, the findings
suggested that spaced repetition contributed to higher vocabulary retention under specific initial
learning conditions identified through the interaction effect observed in the ANCOVA model.
Therefore, support for the alternative hypothesis was interpreted cautiously and in relation to
students’ prior lexical performance. Given that the participants' initial lexical knowledge
conditioned the observed effect, this acceptance was developed cautiously (Esquivel-Gámez &
Berthely-Barrios, 2025; Masache-Escobar & Enciso, 2023; Zhang et al., 2022).
Spaced repetition was found to be an effective strategy for improving vocabulary
retention in A2-level English learners, provided that individual differences at baseline are
considered. This conclusion provided relevant empirical evidence for educational contexts with
limited exposure time and established a solid basis for future research aimed at the differentiated
adaptation of distributed review strategies.
CONCLUSIONS
The study aimed to determine the efficiency of spaced repetition in vocabulary retention
among A2-level English learners. The results showed a significant improvement in the
performance of the group that received the intervention, once the initial level of lexical knowledge
had been controlled for. This evidence provided a direct response to the objective set and
confirmed the relevance of the quantitative approach adopted. The descriptive analysis revealed
significant and similar data between the two study groups (Teng, 2023). After the intervention
was applied, the experimental group achieved a higher level of lexical retention. Therefore, the
temporal organisation of revisions has a significant influence on the process of teaching and
learning the English language. On the other hand, it can be determined that memory stability is
linked to retrieval distributed over time (Alisoy & Sadigzade, 2025; Lee et al., 2021).
The covariance model confirmed that prior performance acted as a predictor of final
performance. Furthermore, the significant interaction between the group and the pretest indicated
that the efficiency of spaced repetition depended on the student's initial level. The treatment did
not produce a uniform effect. This condition provided a more accurate interpretation of the
phenomenon and avoided simplistic interpretations of the impact of the strategy applied
(Alhazmi, 2024).
The study found significant improvements in vocabulary retention after the intervention
to address the objectives. Additionally, the viability of spaced repetition-based activities in an
educational context was confirmed. The experimental group's pre-test and post-test results also
showed statistically significant differences. As a result, these findings validate the study's internal
consistency and the applicability of the tools employed. The null hypothesis, which proposed that
there were no differences in vocabulary retention between groups, was rejected considering the
empirical findings. After controlling for the initial level assessed in the pre-test, the findings
suggested that spaced repetition contributed to higher vocabulary retention under specific initial
learning conditions identified through the interaction effect observed in the ANCOVA model.
Therefore, support for the alternative hypothesis was interpreted cautiously and in relation to
students’ prior lexical performance. Given that the participants' initial lexical knowledge
conditioned the observed effect, this acceptance was developed cautiously (Esquivel-Gámez &
Berthely-Barrios, 2025; Masache-Escobar & Enciso, 2023; Zhang et al., 2022).
Spaced repetition was found to be an effective strategy for improving vocabulary
retention in A2-level English learners, provided that individual differences at baseline are
considered. This conclusion provided relevant empirical evidence for educational contexts with
limited exposure time and established a solid basis for future research aimed at the differentiated
adaptation of distributed review strategies.
Vol. 13/ Núm. 2 2026 pág. 2544
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Journal of English Language, 14(6), 390–399. https://doi.org/10.5430/wjel.v14n6p390
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Traditional Methods in Vocabulary Acquisition. Educational Process: International
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cualitativa y mixta (McGraw Hill).
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model to predict the use of artificial intelligence in experimental science students.
International Electronic Journal of Mathematics Education, 20(1), em0807.
https://doi.org/10.29333/iejme/15736
Krippendorff, K. (2019). Content Analysis: An Introduction to Its Methodology. In Content
Analysis: An Introduction to Its Methodology. SAGE Publications.
https://doi.org/10.4135/9781071878781
Lee, I.-H., Maechtle, C., & Hu, C.-F. (2021). Enhancing Vocabulary Retention in Low-Achieving
EFL Students: Massed or Spaced? English Teaching and Learning, 45(4), 415–430.
https://doi.org/10.1007/s42321-020-00074-y
Li, X. (2025). Spaced repetition as a basic structural method for organizing English as a second
language teaching. Porta Linguarum, 2025(44), 11–28.
https://doi.org/10.30827/portalin.vi44.30170
Masache-Escobar, A., & Enciso, L. (2023). Using Genially to design flashcards to teach English
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