I just completed an open online course on classical music from Yale and Professor Craig Wright. The course took 8 weeks and required a few hours a week of my time. I learned new things and reinforced things I had only partially understood before. Over the weeks I took 74 short quizzes with a total of over 300 questions, and I scored in the low 90s overall. Most of all, I had a good time.
Have you taken a Massive Open Online Course (a "MOOC")? Completed one? Coursera and edX offer a great catalog of interesting courses. You can take them at no cost, or for a very small cost you can "register" for a verified certificate in which case a passing grade gets you an online badge or certificate of completion. If you enjoy learning by reading or watching documentaries, this can be a fun and interactive new way for you to continue to learn.
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