Cleaned up his books on his own!

I've been working with Ian to clean up his books for a couple of years. Usually he takes one down, flips through it, chucks it on the floor and continues on until he is engulfed in a sea of books. As soon as I clean them up he's back to if I'm not right there reminding him  "When you're done with a book you put it back."

You can imagine my jaw dropping when I turned around to see this done all on his own