There are loads of classes available free online from kindergarten all the way through GED and CLEP prep courses. Lots of kids homeschool or struggle with studies and need a little boost. My wife had ADHD and Dyslexia as a kid. She has a Masters in Education and teaches, now. She found a way to compensate. I'll ask her for some tips when she gets home from work. Meantime, I found this site that might help.
Free Online Homeschool Courses 