Open Culture is a website that has a listing of many, many free online courses from top-notch universities. Their link is here. And yes, you read that correctly, they are FREE. Yippee Skippee.
The classes are from Harvard, Yale, Stanford, UC Berkely, Carnegie Mellon, Texas A&M, and the like.
There are hundreds of classes covering a wide range of topics. This is a wonderful opportunity for you to learn something new or for you high school student to pursue an interest before committing to a major.