"Savez-vous planter les choux?" is a preschool crowd pleaser in French.
This is because you plant the cabbage with your body parts. I've done that with pre-schoolers.
Another one they love but you're not going to be able to do it in America is "Chevaliers de la Table Ronde" because it's a drinking ditty. And my little kids wore mustaches and stuff to pretend to be knights of the round table. The reason the kids love it is that the lyrics are funny as they get to say yes and....Non Non Non! with a man's voice, and then the "oui oui oui" with a mousy female voice. It just makes them roll on the floor laughing.
"Chevalier de la table ronde, goutons voir si le vin est bon" (and they taste their wine)
Chevaliers de la table ronde, goutons voir si le vin est bon"
"Goutons voir, oui oui oui, goutons voir, non non non, goutons voir si le vin est bon..."
Don't do the last verses though.
"Si je meurs je veux qu'on m'enterre, dans une cave ou il y a du bon vin...les pieds contre la muraille, et la tete sous le robinet."
If I die please bury me in a cellar where there's good wine, my feet against the wall and my head underneath the spigot.
"Alouette" is always good, they love the gross aspects!
I don't know whether you can do spirituals at your school, but "I'm gonna sing when the spirit says sing." is a rousing good song for children.
I personally find "Whistle while you work" a good song too.
But they can't whistle.