I sympathise. I have a yr 10 class of four (and another of seven) this year and it is incredibly difficult. I have done things like improv circles with them - where one person mimes something and then another joins them and their opening statement makes it clear who they are. The original actor has to accept their suggestion and go with it.After a few secs I freeze them and take original person out and put next person in. Once we'd done it a few times they got quicker and we were able to slot them in and out without my input. I've also done 10 second objects with them. Exactly as it says. They have 10 seconds to form an object with their bodies as a group of four. It can get very silly and it's good for energising them when they can't be bothered. I wish I could energise mine more in terms of working independently. They are so used to getting a lot of teacher input that they can be a bit passive. Which is my fault of course. Good luck!