Free DMV Written Tests and Layover.com each provide online commercial drivers license school bus driver practice tests. Users answer a series of questions, then receive immediate results upon completion of each question or of the entire test.
Free DMV Written Tests offers a test with 25 questions, displaying each question separately. Users can choose to have hints shown after they have attempted answering each question. If the user answers incorrectly, the correct answer is provided and explained.
Layover.com provides a practice test with 16 questions and provides results after all of the questions are answered. The result is given as a percentage, and correct answers are listed for every question.