Well, here is what I do sometimes: I just love to let people talk
instead of me, so I would usually ask a couple of questions to my individual students, listen to their (hopefully) long answers, and then try to connect it to the lesson itself. But, just to make the right impression (and not to let them think I had no time to plan the lesson, which is why I am trying to spend the first 25 minutes just chatting away) I try to use special worksheets for this wake-up-chats. Here are 2 just to show an example, but they can be quite different, containing various questions and looking very different too! (sometimes, when I really don’t have enough time to plan the lesson, I just use post-its for a change).
What is very valuable about such worksheets is that they are completely “open-ended” and easily adaptable for any kind of learner (or a group of learners, too). So if you use these questions to talk to an upper-intermediate student from a law company, you will hear completely different answers (and vocabulary used, too) from a, let’s say, intermediate search engline company enployee. But in both cases your students will get a great oppportunity to refresh (or even aquire) the vocabulary and the grammar they need and want.
So here are the worksheets:
the one containing sentence starters: week overview
the one involving a bit more thinking and grammar training: starting questions – slashed
oh, and please tell me what you do to help your students wake up and “tune in”!