Crazy Conveyor is a free puzzle app game that's really more of an action game.
The object is to place directional arrow on the gray squares to get the blue boxes home.
I've only played it a few times. There's some interesting action going on. Level 2: your boxes must speed up in order to land on a trampoline, land elsewhere, then head back to the trampoline to get to the next level.
I'm not compelled to solve every level. But I think kids would find this fun.