All my sons went with me at various times when they were young and not yet hunting, all carried a BB or pellet gun to learn proper firearms handling, muzzle control etc. They also got to shoot at various non living targets to learn marksmanship. I still have all the guns they use as kids, sometimes when they come over and take them out of the safe they recall/tell stories about when they used them back then.
Have fun, they grow up fast...