What should I do with my teen who does seem to have mastered her classes?

Is your teen a good student?  Here are suggestions for teens.
1.  Review for the ACT or SAT with Up Your Score.  Buy a copy on eBay.
2. Take practice SAT tests.
3. Take a course.  Khan Academy offers complete classes online.  Why?  Use this time to prep for college.  Are you interested in medicine?  Take Anatomy and Physiology or Medical Terminology.  Retake Algebra 2 if you earned a C or below.
4.  Get a library card to access Lynda.com and Overdrive.  Some library systems offer free ebooks and online classes.  Download a free Kindle app.
5.  Use Writing Better Essays in 20 Minutes a Day to learn how to hone your composition skills.
6.  How is your grammar?  Use Easy Grammar.  Buy a copy used on Amazon.  Be sure to get a teacher’s edition, too! You will need to look at the answers.  While you are learning grammar, learn to diagram sentences.  Khan Academy has videos if you need more help.
7.  Read the classics.  Here are 20 books teens should read before they turn 18.
8.  Prepare lessons for their siblings.  Have your child research and organize a core curriculum for her brother or sister in history, math, English, and science.