When my 5th child was but a wee small baby, I started to identify his right from his left.  As I put on his pants I would ask for his right leg or his left leg.  We would do this with his feet when putting on shoes.  At bath time I would identify his body parts as we washed up and then identify what was the right and what was the left.  When he was 2 years old (or younger), he could easily point to his left cheek, his right elbow, his right knee, etc...  This was a very natural way to teach him these things.  I did not do this with my older children, and they are much slower at identifying left from right when I ask them.  When we teach things to our children as babies, we are wiring their brains to think more efficiently.