Just sharing this info: MIT offers many of their lectures and notes online for no fee. The site is called MIT Open Courseware. There are specific courses aimed at high school students, and many of the college's 100 and 200 level courses. Some have video lectures, many have assignments even lecture notes. It's a wonderful resource. There is no instructor feedback or contact, though. This isn't to be used as an online course but more as an independent study. My sons have used it and it has been very valuable.

My husband (MIT '81) used the freshmen physics class lectures when he taught our son and another home school student this year.  The professor had been my DH's TA when he was a freshmen back in the 70s!  The class was an excellent companion to Apologia Physics.

www.academicearth.org is another great site for college level courses.