摘要：This study examines functions of teacher code-switching in secondary school English and science classrooms in Malaysia, where English has recently been implemented as the language of instruction for science. Classroom interaction data were obtained from two English lessons and a science lesson. Analysis of the teachers' code-switching using Gumperz's (1982) semantic model show that code-switching in the two English lessons were vastly different, with little code-switching in the teacher-facilitated lesson. The other lesson, in which English was taught as a content subject was similar to the science lesson in the frequent use and co-occurrence use of code-switching for reiteration and message qualification. The direction of the language switch from English to Bahasa Malaysia as well as the proportion of teacher talk in English suggests that the base language for teaching is still English, even for the science lesson, and code-switching is a necessary tool for teachers to achieve teaching goals in content-based lessons involving students who lack proficiency in the instructional language.
