No person shall operate any school bus owned by or under contract with a public school or the state board of education unless such driver has qualified for a school bus (S) endorsement and complied with the pertinent rules and regulations of the Department of Revenue.  A school bus operator must have successfully passed an examination for the operation of a school bus as prescribed by the director of revenue.  The examination shall include, but need not be limited to, a written skills examination of applicable laws, rules and procedures, and a driving test in the type of vehicle to be operated (302.272, RSMo).