Again, online learning is hard. To break up the monotony of watching video lesson after video lesson, CG Cookie has created Quizzes. These are a great way to to a self-check on what you've consumed from the content you've watched.
Quizzes are usually 4-5 basic questions that will help solidify your knowledge and prepare you for the next course. Each question answered correctly will award XP, so they are an easy way to gain points. If you're not sure of an answer, go ahead and review the previous lessons to make sure you've got it.
You can take a quiz as many times as you'd like, so keep going until you get 100%. Repetition is the best way to learn!