This study sought to determine the effects of flipped learning strategy on NCE Mathematics students’ interest and achievement in trigonometry. The study employed a quasi-experimental 2 x 2 factorial research design. The sample of the study consisted of 60 students, who had a personal computer and Internet access at home. They were randomly assigned into an experimental group of 32 students (22 males, 10 female) and control group of 28 students (20 male, 8 female) The instruments used for data collection during the pre-test and post-test consisted of a trigonometry achievement test (TAT) and trigonometry interest scale (TIS). The TAT was validated by specialists in mathematics education and measurement and evaluation using table of specifications constructed for the multiple choice test items. The multiple choice test had average difficulty and discrimination indices of 0.43 and 0.55 respectively. The reliabilities of the multiple choice test items and trigonometry interest scale were established using the coefficient of internal consistency based on Cronbach Alpha ( ).The reliability coefficients for the TAT and TIS were 0.68 and 0.75 respectively. The data collected from the pre-test and post-test were subjected to statistical analysis using the Statistical Package for Social Sciences (SPSS). The research questions were answered using descriptive statistics while the hypotheses for the study were tested using t-test statistics and the Analysis of Covariance (ANCOVA) with pre-test scores as covariates at 0.05 level of significance. The findings from the study showed that: flipped learning l strategy was more effective than the lecture method in improving students’ academic achievement and interest in trigonometry. The result also shows that there was no significant difference between the achievement of male and female students from the experimental group in trigonometry and that there was no significant interaction effects of treatment and gender on students’ achievement in trigonometry. It was recommended among others that Curriculum planners and educational policy makers should consider a review of the curriculum to incorporate flipped classroom strategy into the Nigeria Certificate in Education Mathematics Curriculum
Keywords: Achievement, Instructional strategy, Interest, flipped learning, trigonometry
