D.L.
Some of it is just excited about knowing this thing really well and some just who he is and what he's drawn to. If it starts to worry you because you think it's a little compulsive just redirect him to something else. Yep thats a circle but hey look at this great square. Can you help Mommy find another one? I have a 5 year old and he goes through periods of focusing in a little too much on certain things and this really works with him.