Meta-analysis of the effects of mastery learning on students’ academic achievements in Nigeria
Authors: Ede Maxwell Okwudili , Igbokwe Uwakwe Okereke 
Published: October 2018

Purpose
The purpose of this paper is fivefold: to identify the various results of previous empirical studies on the effect of mastery learning and students achievement in Nigeria schools; determine the effect size for each of the studies examined; determine the mean effect size of the overall studies examined; find out the mean effect size of studies that examined the effect of gender on academic achievement in mastery learning strategy; and determine the mean effect size of studies that examined the effect of school locations on academic achievements using mastery learning strategy.

Design/methodology/approach
This study adopted survey research design using the ex post facto procedure. This study being meta-analytical used already existing data (research results). The sample of research reports included both published and unpublished research reports on the effects of mastery learning on students’ academic achievements in Nigeria between 1980 and 2016. The study adopted a purposive sampling technique in selecting the sample. This was to ensure that studies: were centered on mastery learning and students’ academic achievements; were carried out in Nigeria; appeared in published and unpublished literature between 1980 and 2016; have the statistical values of the research results of each independent variable to be considered (e.g. t-test values, χ2 values and correlation values).

Findings
The study revealed that the mean effect size for all the studies was 0.536, indicating a positive mean effect size. The strategy, thus, has a significant effect on students’ achievements. School location, also, did not mediate in the use of the strategy.

Practical implications
Based on the findings of this study, the following recommendations were made: teachers should use this teaching strategy to enhance students’ achievements in difficult concepts in different subject areas. Since the result of this study has shown that the strategy has positive and large effect size, government and school proprietors should, with the collaboration of higher institutions concerned with teacher education, endeavor to organize seminars and workshops to serving teachers to enable them embrace effectively the principles and processes of implementing the strategy in the classroom. Since the result of this study has established the size of the effect of mastery learning strategy on the academic achievements, subsequent researchers should no longer direct their efforts in determining its effects on academic achievements but on the ways of improving the use of the strategy in teaching at all levels of education.

Originality/value
Available literature has shown that though most previous research findings revealed that mastery learning approach has an effect on academic achievements of students, no efforts have been made toward resolving the inconsistencies of those results by integrating them and establishing the extent of the effect of the strategy on academic achievements. This study, therefore, was designed to fill these gaps created by the non-existence of integrated studies on effects of mastery learning and academic achievements of students in Nigerian schools.