Many studies have been carried out on this topic. Richard and Lockhart (2000) view the classroom activities as several tasks chosen for achieving particular teaching or learning goals. A teacher should make up his or her mind of what activities to use and when to use them to optimize the instructional goals. From Wilson's standpoint, classroom activity is to assist students to set up appropriate patterns of behavior. Willis (1996) calls these activities as "task chain". Cheng Xiao tang (2004) indicates that activities are particular tasks or say steps for students to complete. A simple activity should be snowballed into more complex activities. And these activities are, in fact, interrelated.

Lee (2000) defines classroom activity that it should bear the following four characteristics. To start with, it should be a target achievable by the interaction among participants. Secondly, there exists a mechanism for building and sequencing interaction. Furthermore, it is centralization on meaning exchange. And at last, it features a language learning endeavor that calls for learners to understand, operate, and generate the target language when they conduct some set of work plans, (cited in Zhou, 2007). Prabhu (1987) deems that an activity required learners to achieve at an outcome from given information through some course of thought and allowed teachers to charge and regulate that course is regarded as a task. Richards and Weber (1985) claim that an activity or action which is carried out as the final result of processing or understanding language, or put it into another word, as a response. For instance, drawing a chart while listening to a tape, or listening to an instruction and conducting a command. An effective task usually depends on whether it has a successful effect or not. The use of different types of tasks in language teaching will make teaching more communicative for it provides a goal for classroom activity which exceeds the practice of language for its own sake. In this thesis, the classroom activities mentioned mainly refer to those serving for accomplishing certain tasks.