Umm, lots of forward rolls. Setup a block for them to practice kickovers on.
If they let you, get some rope and tie them to a bar with it to make a hip circle machine. Some kids will utterly hate this and others will never want to stop spinny around.
Lots of hanging stuff. Do side to side and hand over hand walks from one side of the High Bar to the other and make them hold a pit cube or beany bag with their feet. Of course they can just drop into a pit as well if it's a pit bar.