My dd went to a public pre-K, attached to an elementary school. They bumped her up in an informal skip. She was able to meet with the k'ers, in their highest group, so she received more challenge in reading, writing and math (But she did coloring, specials and recess with the pre-k'ers.). If there are higher grades in this school, it seems reasonable that your son could go to the other classes for challenge. What do the teachers say about that?