AbstractThe purpose of this study was to determine the effectiveness of an interactive geometry software program, Geometer’s Sketchpad (GSP), in the teaching and learning of mathematics among technical schools’ students. The quasi-experimental study was conducted on 56 students from a randomly selected technical school. The students were assigned into a controlled and an experimental group using cluster (class-based) random sampling. The control group received conventional teaching method while the experimental group was taught using a GSP module on a chosen topic namely Trigonometric Functions for the duration of 8 weeks. Three sets of tests, which are pre-test, post-test and retention-test were administered to both groups of students in weeks 1, 8 and 10, respectively. Besides the tests, a set of questionnaires and an interview protocol were used in collecting the empirical data. The results of tests and questionnaires were analysed using descriptive and inferential statistics such as me.....