Mashalim can work well… Not sure if a three year old brain can make the transfer though.
I haven’t finished thinking this one through so it’s pretty rough.
” Imagine if you were building a block tower with your best friend Moshe in playgroup. It’s already three stories high, and there is a moat with alligators, 2 pointy towers, with windows… And you are putting on the last tower and another boy is being silly and running around and he runs straight into your block tower and knocks it down! So your morah has the boy sit in time out. Then another boy comes and gives the morah a potch! Is that OK?”
Something along those lines… I am not a parent – so please let me know if this will backfire 🙂