That is awesome! Congrats to your DS! I have an almost-6-year-old who loves to help me cook and bake, but I hadn't thought about letting him tackle something like a quick bread. But it's a great idea.
One thing, about using a knifei -- it's my understanding that a dull knife is more dangerous than a sharp one, because it can do a lot worse damage if you do cut yourself with it. So that may not be the way you want to go. Just MHO.
"We reject as false the choice between our safety and our ideals. Our founding fathers, faced with perils we can scarcely imagine, drafted a charter to assure the rule of law and the rights of man, a charter expanded by the blood of generations. Those ideals still light the world, and we will not give them up for expedience's sake."
--President Barack Obama, 1/20/09