I taught Coco by asking her to go "down", then I would say "bang" and gently roll her to her side and keep my hand on her, then praise the heck out of her. Within literally 5 minutes, she was doing it by herself, and I incorporated the hand gesture in. Now I don't even have to say anything, I just point my finger at her and she's down. You can see Coco's bang trick at
www.dropshots.com/cocosmom
It's the one labeled August 28