If your child is a little older, and you're trying to teach him what is new, then you just need to make it so. that would not completely discourage him the desire to learn. After all, he knows everything and is able, and you and your notations, and lessons learned. But while it's all in the future, and now you're trying to teach him not to just say the name of numbers, but also to know how they are written, and look, it's hard to be all that.