This trick is easy. I had a nice thick piece of cardboard that I covered with a scrap of fabric (but you could do this on a bulletin board or wall somewhere). The fabric board is then covered with large size bubble wrap and I hung it with s hooks and a little rope. Any time a kid does something awesome they get to go "pop a bubble" or "pop a popper." Kids love it. My rule is that we all stop to listen to the chosen kid pop and then we clap for them. Kids love it, they work for it, and it's so easy to make.
I work a part-time retail job and they give me all the bubble wrap that is used to package props and sale items. I get it for free but I think that you can get it pretty cheap on a big roll at UPS or at an office supply store. Debbie staples the bubble wrap to a bulletin board (which is probably easier than what I do). She uses wrapping paper or butcher paper behind the bubble wrap to change the look of it. It's super easy to pull off and is actually pretty fun. I mean, who doesn't like bubble wrap!