We also did waterfall pose and some students started crawling around with someone on their back turning it into a "ride." They were giggling and laughing as they were moved around the room.
Headstands are a problem because most students need help getting their legs up so I enlisted people to be headstand and handstand assistants. The kids loved being a helper and it eliminated the need for being everywhere at once.
Svasana was interesting because many preferred to lay on the floor instead of their mats. I guess they all wanted to be more grounded. ;-)