One day this week Nolan woke up and discovered this puzzle was easy. He can take all the pieces off and put them on the right place. He can make matches. No longer is there a duck-sheep. Now all the animals are matched properly and the congratulatory song is sung. And more so, no longer is there frustrated throwing of the pieces across the floor. Well, not much of it anyway. It's amazing how much they develop. Truly, it happened overnight that he can solve this puzzle. Really cool to watch this kiddo develop.