Extra practice problems for every unit, with instant feedback.
How these work. Pick a unit. Choose a difficulty level and how many questions you want, then answer them one at a time.
You find out immediately whether you were right, and every question comes with a full explanation — including why the tempting wrong answer is wrong.
At the end you get a list of the skills to review. Nothing is graded and nothing is sent to me; this is purely for your own practice.