A valid driver's license or learner's permit is a must for anybody operating a motor vehicle on Idaho's public roadways. To take the written knowledge and skills tests, applicants must be at least 15 years old. The Idaho written knowledge test is based on the contents of the ID DMV Driver's Manual, which includes road rules, highway signs, traffic signals, pavement markings, safe driving practices, and needed motor vehicle equipment. The Idaho DMV written test has 40 questions, and you can only fail the test if you miss 6 of them. Let's start with our Idaho driving test now.