Tree pose takes on a whole new dimension of balance challenge when you have the children take the form of a craggy, creaky, crabby, bare limbed and rickety tree. Have them change arm positions while balancing on one leg, then hold the arm position while switching legs. Try trees blowing the wind - and let them have fun (gently) falling over.
Something I'd like to try with an older group, after setting some ground rules (e.g, no touching, no getting too much in someone's face): One student can be the wind and walk around the room blowing (gently) on the other trees. See how this affects the standing ones! We all know that just having a teacher walk NEAR us while practicing balancing poses can throw us off balance. I think this could be fun!
Scary cats on a fence is something I'm going to introduce with the young ones this week at MKC - let them caterwaul while exhaling into strong arched backs, long tails reaching down, for a really good spinal release! Then we're going to go into cat crawl (a modified up dog/lizard style pose) and creep along the floor, claws extended, hunting for "mice" (aka cotton balls)!
I also have a little ditty I composed while teaching at the JCC esp. for the little littles: it's called The Tiny Yoga Spider (to the tune of Itsy Bitsy Spider). For 2 and up, I mention that a spider has four arms and four legs (or 8 legs)...
Start on all fours, on the yoga mat
The Tiny Yoga Spider was on his yoga mat
Arch back low, crown of head up, tails up
First he was a cow
Arch back high
And then he was a cat
Now, lift one arm at a time, go around to each arm twice
Then he wiggled his arms, his arms, his arms, his arms
(breath) Lift each leg twice
Then he wiggled his legs, his legs, his legs, his legs
Curl up into child's pose, slowly
Then the tiny yoga spider, was ready for his bed.