Is it possible to validate college courses by taking a test? For example, I took an online class about electrical engineering (via edX), but no credit was given. But I have gained an understanding in that subject, so I was wondering if I could take a validation test for it. Also, what about subjects that you have self studied? I have an interest in math, and have studied/am studying differential equations, linear algebra, and real analysis. Is it possible for me to take a validation test for those? Also, if it is possible to take a test, when are they administered? During basic training? Before basic? Or before the academic year? Thanks in advance!