Quizzes are for finding out what you know. Your score is based on your first answer to each question, and you can fix your errors at the end of a quiz to help you do better on the next one!
Practice assignments are for you to work on improving what you know. Practice allows you to correct your mistakes as you go, and you can view hints and lessons whenever you make mistakes. You will progress through four levels to reach mastery.
Diagnostics are for figuring out your starting point. Your goal is to work your way to the end of the diagnostic so that your teacher can see what you already know. Don't worry, Diagnostics will not be added to the grade book.