Do you have issues remembering what you learn? Sure, we've all studied these topics before in school but have forgotten since. I brush up on some geometry or li

Do you have issues remembering what you learn? Sure, we've all studied these topics before in school but have forgotten since. I brush up on some geometry or linear algebra every now and then for work. But I'm sure I'll forget if I don't use it after a year or two. Are there any projects you maintain to keep your knowledge fresh?