The New York City private schools that offer special education services tend to be small and well structured. The classes typically vary from six to twelve students with various specialists who assist children during class. The classes also tend to serve students of mixed ages, since children with disabilities learn at varying rates that do not necessarily correlate with age. Most importantly, all of the good private schools aim to integrate students with disabilities into regular classes as soon as possible. Finally, the private schools can be very costly; however, the track records of the good ones are undisputable, mainstreaming special education students at very early ages and often sending some students to elite colleges.