Speaking activities can be used at any stage. Indeed, a direct opposite of what we have just described is a kind of 'boomerang' procedure, where students are involved in a speaking activity and it is their performance in this activity that helps the teacher to decide what to teach next. Speaking activities are often part of longer sequences (as discussed above). Teachers may use speaking activities as welcome relief from more concentrated study, or as a way of seeing how well students have been learning over the last few days or weeks. (来源：EnglishCN.com)

What do teachers have to do?
It is vitally important to be sure beforehand what students need to know for the activity to be successful and to make sure that they are given suitable information or provided with key language.

Tell them the purpose of the task, how they should carry it out, how long they have got. If this is the first time they have used an information gap activity, for example, they must be told not to look at each other's material.

Many teachers prefer to demonstrate an activity before getting students to do it. Such demonstration clarifies the procedures in a way that instructions sometimes do not.

How should teachers correct speaking?
When teachers are conducting drills or checking written homework they often correct all the mistakes they hear or see immediately they hear or see them. But if they do the same when a student is trying to speak fluently, they may throw the student off balance and make fluency impossible. It will also suggest that the teacher is more concerned with the 'how' than with the 'what' of what is said.

Of course there are times during speaking activities when teachers may intervene gently to help out a communication problem (though he or she should consider how important this is and whether or not it might disrupt the activity), but in general it is better for the teacher to listen to what the students are saying, intervene as little as possible, and then give feedback when the activity is finished. First they should tell students what they liked about the activity and comment on the ideas conveyed and then go on to point out mistakes, and do some work to correct them.