Apparently Miles figured out that Jackson isn't meant to be ridden like his rocking horse.

Today at school Miles' favorite farm book was back from the library; and the teachers said that Miles couldn't be happier. He walked around with it under his arm all day, trying to find an empty spot in the classroom to sit and read it. If he couldn't find a spot to read it himself, he walked to a teacher, turned around and plopped down in their laps, waiting for them to read it.