I. Introduction
It is a well acknowledged concept that managing and teaching large-sized classes tend to be problematic. However， large class size does not always constrain teaching and learning outcomes. Studies have also shown that it is the pedagogy that matters rather than the student number. Based on the evidence， this paper proposes teaching strategies for enhancing comprehensible input and encouraging sufficient output in large-sized. It concludes with pedagogical implications for teaching large classes in China for EFL teachers.
Much of the empirical evidence of teaching principles regarding how to minimize the problems and how to foster the advantages of large-sized classes focused on general strategies dealing with large-sized language classroom， which including teamwork and grouping technique would contribute as impressive resources and data for further studies. However， the lack of research on some specific instructional or teaching methods may also constrain the future work. In this paper， several specific teaching theories contributing to large-sized EFL classes will be discussed as implications for future study. These strategies will be categorized into two sections including a） how to enhance comprehensible input to a large amount of audience; b） how to encourage accurate and fluent output in large-sized EFL classes.
II. Enhance the comprehensible input
In his work， Krashen （1985） mentioned that learners acquired language when exposed to sufficient comprehensible input of language materials （e.g. visuals， texts， music， TPR （i.e. total physical response））. However， the large amount of audience with different language proficiency and interest in Chinese college EFL classes constrains the selection of teaching and extending materials. Two teaching theoretical strategies may serve to solve this problem.
2.1 Content-based instruction
As defined in Wolf’s （2002） work， Content-based instruction （CBI） is a general term referring to language teaching approaches that contribute to both two but not equal objectives focused on language and content-learning （e.g. culture， subject area）. CBI has been applied to practice in various ways corresponding to student needs. “Unlike other language instruction approaches that define primary content in terms of grammatical structures， communicative language functions， or language skills，， in CBI， content refers to the use of nonlanguage subject matter that is closely aligned with traditional school subjects， themes of interest to students， or vocational and occupational areas （Stoller， 2008）.”
