I am a 47 year old who decided to finally get my high school diploma after 30 years. I unintentionally ran across Khan Academy in an attempt to 'brush-up' on math.
I noticed that Sal Khan has this 'relaxed' way of speaking while explaining how to do math that causes you to also relax as you learn. That made learning very easy. It kept my interest and actually made it sort of fun.
After 30 years having no dealings with academic studies whatsoever, I studied with Khan Academy for a few months and received an overall 82% on my TASC Test (which I discovered has been a replacement for the traditional G. E. D. Of my generation). For math specifically, I received a 78%.
They have a fantastic thing going on there and I would recommend it to any and everyone! Highly effective.