This endorsement is required for driving a school bus. To receive this endorsement, applicants must pass a test. The test consists of 20 multiple choice questions. To pass, the applicant must answer at least 16 questions correctly. Each question has three possible answer choices. Test questions come from the Iowa Commercial Driver License Manual. Questions come from chapters covering School Buses, Pre-Trip Vehicle Inspection Test, Basic Vehicle Control Skills Test and On-Road Driving. The School Bus endorsement can be used with the Class A, B or C CDL.