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]

The aim of this study was to investigate vocabulary knowledge and growth across two different language-learning programmes in Hong Kong. The two programmes compared were English immersion programmes (IM) and regular English second-language programmes (RL2). While previous research has identified an overall advantage to IM with respect to language development, comparatively little research on vocabulary development in IM has examined the potential interaction between different types of words (in terms of frequency levels) and different types of vocabulary (passive versus active). Furthermore, very little work has compared these two specific educational contexts in Hong Kong with respect to vocabulary growth. Therefore, three different aspects of vocabulary were measured: passive, controlled active and free active word knowledge at different word-frequency levels in grade 7 and grade 9 students in both IM and RL2. The Vocabulary Levels Tests measured students' knowledge of passive and controlled active vocabulary, whereas students' writing was analysed with the Lexical Frequency Profiles to estimate their free active vocabulary knowledge. Overall, IM students outperform their counterparts in RL2 concerning their knowledge of different types of vocabulary at various frequency levels. IM students also experience a more rapid growth in their vocabulary knowledge, especially for the most frequent 2000 words and academic vocabulary. Such findings support the claim that IM can provide a more favourable context for L2 vocabulary learning than regular L2. The results of the present study are discussed in terms of wider implications for vocabulary learning and the effectiveness of the IM programmes implemented in Hong Kong.
[Copyright of Language and Education is the property of Routledge. Full article may be available at the publisher's website:
http://dx.doi.org/10.1080/09500780903576125]