Recent and relevant studies had proved that most of the students struggled in their three major subjects: English, Mathematics and Science. Aside from their poor performance based on the various national and internal tests like the Programme for International Student Assessment (PISA) and Trends in International Mathematics and Science Study (TIMSS), it had been observed also that they had difficulty in doing their performance tasks because they commonly do one performance task per subject. The number of performance task they are doing per quarter are bombarding the students. The rationale of this study is to apply the thematic instruction in English , Math and Science in conducting the lesson and in creation of an integrative performance task and test its effectivity for the experimental group. The study used descriptive quantitative design. A pretest and posttest was given to them to test the effectivity of applying the thematic instruction in teaching. A survey questionnaire was also given to know their perceptions on the level of effectivity of the thematic instruction in an integrative performance task. The result shows that there is a significant difference between the result of the pretest and posttest where a significant improvement was seen. Furthermore from the result of the survey, there is a positive perception on the level of effectivity of the thematic instruction in the conduct of the integrative performance task.

Keywords : Education, Teaching, Thematic Instruction, Integrative Performance Task, Descriptive Quantitative Design.