Find out about how students are assessed and how progress is determined. Some pre schools are very much designed like a regular school program, whereas others are based more on individual student progress rather than against other students in the class or group.
If your child has special needs such as a physical disability, developmental disability or mental disability it is important to find out how much experience the school has with interacting and successfully working with this type of student. Ask if the school is open to having outside professionals in the school should this be required.