we see this with DS5 - sometimes he likes to read a chapter book (or start it then put it aside for a long, long time) and then sometimes he just wants to read Splat the Cat or Garfield comics.
At home, we just leave books out of all levels and topics (and since he has a younger sister, we have a lot of "girl" books that he is welcome to read, and does read) and some days, he is more interested in crashing his hot wheel cars than reading. I find our kids swings back and forth all the time - sometimes wanting more advanced books/stuff then sometimes just wanting their stuffed animals and cars to play with for hours. We just make a wide range of activities available at this age.
