The other day I had a student tell me she felt too wired and she didn't want to sit down. She asked me if she could stand up in the back of the room. I didn't see what the big deal would be. Of course 2 others wanted to do it too. They both stood at my podium and took notes there, and the other girl stood in the back and just bent over a desk. It wasn't a problem at all. Do you let students stand? I have seen classrooms with higher desks. I guess if you had a bar height counter, students could sit at a stool or stand. As long as they didn't start dancing around and being silly, I don't think it would be a problem. Sometimes I feel bad for them sitting all day.