Is my 3 year old normal?

What ever you are doing with keep doing.. kids at that age learn by involvement .. its sounds like you always talk with him and explain things to him and that's normal .. continue feeding him information .. all kids have the capabilities to do these things at this age but if the parents don't foster it no one ever knows.. so he's just doing what you have taught him and the interaction that you have with him... so keep up the good work and encourage your friends around you to do the same with their kids so the kids of America can compete in the world. Thumbs up to YOU !!!