id say things like shrimping competitions up the mat. swiss balls sprawls. who can stay on mount the longest. forward and backward rolls. jacare down the mats. starting in something like 50/50 and seeing who can get to top control first.
use lots of stories to explain thing. like if you show an americana, explain to grip like a four and then mention the motorbike grip and make noises and then hug it towards you becuase we want to make them like a dinosaur with small arms, (thats pretty much off the top of my head,) dont judge