Originally Posted by Off Road
I agree. For my son, I started him on bar dips and light military press when he could do 3 sets of 20 reps on his push-ups. I think you have to take the individual into consideration, but either way, 100 push-ups is a LOT.
Your son is fortunate that he has someone with good knowledge guiding him for sure.
I do agree that 100 reps for push ups is a lot (My PR for one set is about half that) but having some bodyweight training as a novice can really only be of great benefit prior to getting your mitts on the weights. Dips and chins/pulls are also a win.