Dump all the above ingredients (except the sauce) into a large bowl and, with your (clean) bare hands (or your child’s) or a mixing spoon, thoroughly combine everything until it is well mixed. With wet hands, form the meat mixture into 1 in. (2.5 cm) diameter balls, rolling them firmly. (Be sure to remind your child not to taste the raw meat mixture and to wash his hands as soon as he’s finished rolling meatballs.)
Place on an ungreased baking sheet and bake at 375°F (190°C) for 15 to 20 minutes, turning them over halfway through baking. The meatballs should be firm, and slightly browned.
Meanwhile, heat the spaghetti sauce in a medium saucepan. Remove meatballs from baking sheet and plunk into the simmering sauce. Allow to simmer in the sauce for 15 to 20 minutes.