I personally like classes that are lively and sometimes bordering on boisterous. There is fine line between happy involvement and a party and I sometimes have to manage that with redirection. At the other extreme, I have never received what I consider a good instructor rating from a quiet class, which may help explain my preference. For a quiet class, I know that I have to prod, so I will sometimes ask why no one has asked me a question about _____________________ (I mention something specific and relevant). Again, silence. Again I ask, 'seriously, don't you want to know?'......more silence and then a timid 'yes' from someone. Then I say, 'well, ask me!' Sometimes at this point someone will ask and I will thank them for asking :-), Sometimes, I get sheepish smiles but no one is asking. At which point, I say, 'ok, well, if you are ever interested just ask. Till then, we move on.' And then, I just leave it hanging. They get a little perturbed that I would not just give it to them but it tends to open the door to having them take more responsibility for their learning. With a few more of these espisodes, by the 2nd or 3rd week of class, they will typically have come around to being more involved.