Bus drivers must have a commercial driver license if they drive a vehicle designed to seat more than 15 persons, including the driver. Bus drivers must have a passenger endorsement on their CDL. To get the P endorsement you must pass a knowledge test on Sections 2 (driving safely) and Section 4 (Passenger). The skills test must also be passed for the type of vehicle to be driven.
The included online practice tests cover all material covered in Section 4 (Passenger). Note that in order to drive a school bus, an additional school bus endorsement must be received.