Since the 1960s, there has been an increasing attempt in research on teaching and learning from instruction to relate the major features of teacher and student behavior in classrooms to learning outcomes. There have been extensive investigations into the types and quantities of instructional and noninstructional tasks, the relative amounts of participation by the teacher and students, and the functions and forms of language in interaction. At the same time, various personality, attitudinal, cognitive, and other individual or social factors which are thought to influence observable classroom behaviors have been the object of instructional research. The fundamental goal of most such research has, of course, been to determine which variables best, or more frequently, lead to academic achievement. Careful evaluation of results can lead to well-informed decision making at all levels of educational planning: development of the curriculum, preparation of materials, training of teachers, preference for classroom teaching activities and techniques, decisions about individualization of instruction, and even teacher's modifications of speech in explanations. The range of applications of classroom- based research is broad, and the number of factors and issues studied seems endless. While second language classroom research has tended to lag behind native language research in the topics and methods for investigation, these statements apply equally to both contexts.

In addition to the intrinsic interest that the description of classroom processes has for researchers, probably the ultimate objective of classroom research is to identify those characteristics of classrooms that lead to efficient learning of the instructional content, so that empirically supported L2 teacher training and program development can be implemented.