My dad used to point at a part and ask me what it was( water pump, distributor, carb, etc.) eventually I new what all the parts were and where they went. Eventually it was tearing things apart and putting them back together. I try and do that with my daughter, but I think she may still be a bit young. It's cool that your son isn't afraid to climb up with dad in the engine compartment and get dirty. And I agree that , that is a picture worth being framed.