Repetition helps memory which is why they keep asking the same damn thing over and over (and also why they want the same books over and over etc).
This is definitely a great way to help things sink in XD Siblings explaining things to each other works just as well too :)
yes, siblings are great, but he is my only one son for now, so I am his pupil:))
If it's any consolation, even if there are siblings you will still end up being someone's pupil at some stage. For me now it's a lot of maths and physics that I don't understand with my 17yo and I am the slow pupil XD