Wayside School
Wayside isn't your ordinary school --- there are 30 classrooms, one on top of the other, making it 30 stories tall! That may be why all kinds of funny things happen at Wayside School...especially on the 13th floor.
You'll meet Mrs. Gorf, the meanest teacher of all; terrible Todd, who always gets sent home early; and John who can read only upside down --- along with all the other kids in the crazy mixed-up school that came out sideways.
Links:
Official Website (Educator Materials available)
Books in this series