CD arranger

No doubt Ethan likes to play with the CD in the player but mother doesn't know why he wants to arrange it on the floor. Bad things that he had done to these CDs was that he pushed them on the floor. He was scolded by mother for doing this. He treats this CD same as his books. Yup, he likes to arrange the books into one line and pushes them. Don't know whether is it because his wants to made the books like a train? Seems like it might be time to buy him a set of train?