We suggest the difficulty level best for you, so you'll never get questions that are too easy or too difficult. If you get stuck, you can use the hints or rewatch the video, and if you're already comfortable with a topic, you'll get challenging questions to stretch your skills!

Passively absorbing new material often isn't enough to really understand it, and multiple choice exercises aren't always the best way to really test your knowledge! We offer a variety of different multimedia exercises that aren't possible on paper.

What's the use of an exercise if you don't understand how well you did — or even worse, end up confused and thinking the wrong answers are right? Our instant feedback and clear, detailed answer explanations help you get the most out of your practice, even after you've already answered the questions.