The role of the first language (L1) in second language (L2) learning has been widely discussed and researched in the second Language Acquisition (SLA) literature. Benefits of L1 use have been found for vocabulary acquisition, and in facilitating comprehension thereby alleviating student anxiety. Many teachers appear to consider L1 use as a necessary option in L2 pedagogy. Disadvantages of L1 use are argued to be that it reduces exposure to the L2 thereby not enabling more implicit forms of L2 acquisition. Considerably less research has been carried out in English medium instruction (EMI) classrooms, surprisingly, as these are predicated on the benefits of massive exposure to the L2. This study investigated the effect of L1 and L2 use on teacher question types and interaction patterns in science lessons in early EMI and late EMI schools in Hong Kong. Our findings show that in late EMI, where there was much greater use of the L1, teachers tended to use higher order questions and were more interactive. In early EMI, despite students having received four more years of greater exposure to English instruction than late EMI students through the use of English as the vehicular language, teachers asked lower order questions and the interaction was more monologic. The implications for policy and pedagogy are discussed.
[Copyright of International Journal of Bilingual Education and Bilingualism is the property of Routledge.]

Teacher-student interaction in classrooms is perceived to be crucial for learning. Previous research has compared the interaction in classrooms where a second language is used as the medium of instruction (MoI) with those where the mother tongue is used. This has been done mainly via qualitative impressions. The current study adopted a mixed method design to examine objectively and comprehensively the classroom interaction in a sample of Hong Kong secondary schools that used Chinese as the MoI from Grade 7 to 9, but then switched to English from Grade 10 onwards (i.e. MoI-switching schools). By doing so, this study aimed to identify the possible effect of a change in the MoI on classroom interaction and its potential for learning. Sixty lessons were observed in Grade 9 and 10 in three MoI-switching schools and compared to two schools where English was used throughout all the grades. The results show that, when the MoI changed from students' first to second language, lessons tended to become more teacher-centred and there were fewer opportunities for negotiation of meaning and scaffolding. These findings have significant implications for the relationship between the MoI and classroom interaction and provide important insights into pedagogy and teacher development.
[Copyright of International Journal of Bilingual Education and Bilingualism is the property of Routledge. Full article may be available at the publisher's website:
http://dx.doi.org/10.1080/13670050.2011.588307]