As others have said, Khan Academy is great. I used it to prep for the GRE after being of college for 5 years. I took my answering very seriously, so I would onl

As others have said, Khan Academy is great. I used it to prep for the GRE after being of college for 5 years. I took my answering very seriously, so I would only move forward if I got 5 questions in a row correct. If I continued to answer wrong, review the session. If you have the time, community colleges are also a worthwhile approach (if you have one). Their entire purpose is to help strengthen the community. Many are taught as distance courses or even night courses because they recognize that the people that need this education probably can't afford to attend during traditional school hours. Finally, it adds a small level of accountability to your education. You paid money for the class, there is a specified time and grading rubric for class which forces you to continue while something like KA or other MOOCs have very high attrition rates.