Nicely done. Parenting for the win. Teaching is the ultimate stage of learning. Here, you can easily determine what you do or don't know. All the holes in your understanding just pop up one by one as you try to explain it. Plus you have think in creative ways a lot of times to get the point across.

For your son to learn this at such an early age, sets the stage for his continual success, and for him to be a creative and imaginative thinker who can easily adjust to any situation.