EFFECTIVENESS OF BILINGUAL INSTRUCTION ON THE PERFORMANCE OF SECONDARY STUDENTS IN SCIENCE AT KAJONKIETSUKA SCHOOL, PHUKET, THAILAND: BASIS FOR ENHANCEMENT PROGRAM

Abstract

This study determined the effectiveness of bilingual instruction on the Science performance of Grade 9 students at Kajonkietsuksa School, Phuket, Thailand. The study employed a quasi-experimental pretest–posttest design involving two intact classes: one exposed to bilingual instruction (English and Thai Star Program) and another to English-only instruction (English I-Star Program). The focus of the instructional intervention was on Genetics, including DNA, RNA, and genes, and it was conducted over a four-week period. Data were collected using a 30-item Science Achievement Test and a student perception survey, supported by qualitative interviews. Results revealed that both groups improved on their posttest scores; however, the bilingual group demonstrated significantly greater gains than the English-only group. Furthermore, students showed positive perceptions of bilingual instruction, particularly regarding improved understanding, engagement, and confidence in learning Science. A significant relationship was found between students’ perception and their academic performance. The findings indicate that bilingual instruction enhances conceptual understanding and reduces language barriers in Science learning. The study concludes that integrating students’ first language alongside English is an effective instructional approach. It is recommended that bilingual strategies be incorporated into Science teaching to improve both academic performance and student engagement.