Test your skills.
GarageBand listens to you play in real time and tells you how you’re doing. Watch the video
“How Did I Play?”
First GarageBand taught you how to play. Now it tests your chops. As you play along with any lesson, record yourself. GarageBand listens in real time and tells you how you’re doing. You’ll see how well you played with colored notes, a progress bar, and a performance meter. You can check your rhythm and note accuracy, keep track of your progress, and beat your best score — all while perfecting your skills.
via apple.com