I believe the official CPS policy is maintained in the teacher contract. It's really a goal for class size, and it's used to allocate classroom teachers to each school based on enrollment. I don't believe that ancillary teachers are included. But, the Assistant Principal usually is. If the AP isn't also teaching a class, then you're already going to have higher class sizes than the policy. Schools (i.e. principals) are given significant flexibility in choosing to combine classes or assign classroom responsibilities to APs, curriculum specialists, or other positions. So, you might first ask your principal, local school council, or union representative about options for addressing high class sizes in your school.