Mastering the shape sorter

CJ loves his puzzles! We spend hours sitting with him while he finds all the matching pieces and puts them together. However, he is still trying to master the shape ball. He can post all the shapes through the slots, even turning them around to make sure they fit. What he still hasn't figured out is matching the slot to the shape - he still gets me to help him with that.

It's nice to still feel needed as I am sure it won't be long before he has figured it out and no longer wants help from me.