I took a semester off of math to do work on dual credit classes for college, I am now returning to Khan Academy to start prep for my SAT.  Although I have completed many of the courses required for the questions on the SAT, after a semester off I have forgotten the required details. If there was a quiz similar to the course challenge, that only showed things you have already completed and it did not affect Mastery level it would allow students  to check and review skills after a break. 

Thank you for your consideration.