In the research literature on classroom interaction, it has been found that teacher talk occupies anywhere from 70 to 80 percent of all interactions in the classroom. And the other 20 to 30 percent of the time is shared among all the other students in the class. For English learners in the classroom, having to share the other 20 percent with all the other kids is not going to give very much time for these youngsters to acquire English.
What we advocate and what we know from research is that we must provide a good, greater amount of time in which students are speaking with each other and interacting with the teacher and among themselves. Now this will not happen unless teachers carefully plan lessons where students are interacting with each other throughout the lesson and throughout the day. One of the ways that teachers can promote interaction in the classroom is through incorporating a variety of activities that require cooperative learning.
And by this I don't mean just putting kids in groups, but really structuring discussion for them. Having them be required to complete a task together in which they have to talk and work and share with each other all builds interaction opportunities.