Evaluation of the effects of medium of instruction on the science learning of Hong Kong secondary students: Performance on the science achievement test

Bilingual Research Journal, Summer 2003 by Yip, Din Yan, Tsang, Wing Kwong, Cheung, Sin Pui

While the findings of the above studies regarding the effects of MOI on student achievement are inconclusive and sometimes conflicting, some generalizations can be drawn to guide policy making on the medium of instruction for schools in Hong Kong. There is evidence that instruction in English or in mixed code has negative effects on learning for low-ability students. However, the negative effects may decrease as students' English proficiency improves. For high-ability students who have reached a threshold proficiency in both languages, using English as the MOI may enhance language acquisition, particularly in English. For these students, achievement in different content subjects may be affected to a lesser degree.

The Education Department's rationale for the 1997 language policy is consistent with these findings. The designation of most secondary schools into the CMI stream and a small number of schools into the EMI stream, and the strict observance of the language of instruction, are based on the observation that children learn best in their mother tongue. Learning through English, a second language to the Chinese students, can be effective only when the students have reached an adequate level of English proficiency. This policy can hopefully provide an optimal learning environment for students of different language proficiencies and capabilities.

Design of the Study

In order to investigate the effects of the MOI policy on the science learning of secondary students, the present study tracked the progress in science achievement of a cohort of students who entered S1 in September 1999 for 3 consecutive years. The science achievement of the students in the different MOI streams was assessed by a written test near the end of each academic year in S1, S2, and S3.

The 100 secondary schools involved in this study were sampled by the stratified random sampling method. Twenty-five schools were randomly selected from the 114 EMI schools, which in general take in students of the highest academic ability. Approximately 300 CMI schools were divided into high-, medium-, and low-ability strata (CHIG, CMID, and CLOW) according to the mean Academic Aptitude Index (AAI) scores of their S1 student intake. The AAI of a student is a score based on the student's academic performance in school-based examinations in Primary 5 and Primary 6 (Grades 5 and 6), the last 2 years of primary education, moderated by a public aptitude test. Twenty-five schools were randomly selected from each stratum, resulting in a total of 75 CMI schools. This sampling design ensured that the study would cover a representative sample of junior secondary school students in terms of academic ability.

The study used both quantitative and qualitative methods to assess the effects of the MOI on science learning. The quantitative study was based on the performance of the four school strata on the multiple-choice and free-response questions in the science achievement test administered for 3 consecutive years starting in the 1999-2000 academic school year. The Education Department provided the AAI scores of the students participating in this project, which served as a measure of students' pretest scores of academic performance.