Spaced repetition comes up in discussions of optimal learning. Once one learns something, it’s best to review it after a period of time, then a second review, third, etc.. with the time between the reviews increasing. There are class structures and software packages which implement this. (Randomly over the years I’ve even considered dumping everything I ever wanted to learn into such a system.)
Part of the power of the spacing is that you don’t come to expect when a particular bit of information will be reviewed. “Oh! I need that knowledge, I guess it is important.” It all apparently causes the brain to not allow the knowledge to expire and be lost. I’ve discovered that my regular usage of the slipbox is randomly, (in the sense that I have no sense of what or when to expect to bump into an idea again,) reminding me of things.
For example, I had a slip, “4c2se1j” with an idea for a blog post on it. As I was writing the post, which involved Sönke Ahrens, I flipped to her name in the slipbox to add this slip’s address to things related to her. She’s on the slip at “4c1ae(3)”. (Because “4c1ae” overflowed to a second “4c1ae(2)” and then third slip “4c1ae(3)”.) Next to her name I added “4c2se1j”. Your eyes may have glassed over, but that’s just another random moment in my using the slipbox—nothing particularly interesting there.
While doing that, my eyes flashed across two addresses already on Ahren’s line…
First, “2ho1”. Just four characters, but I instantly recognized the “2” as a book reference, and Ahren’s book is “HOw to take smart notes.” Several of the ideas from the book flashed through my mind.
Second, “4c2ko1a”. That looks gnarly, but “4c2” is themes. “4c2ko” then must be a word with first-letter K, and first-vowel O, and it has to be related to Ahrens? …that’s easy. That would be the slip for “KnOwledge systems”. I don’t know for sure (without looking) what’s on “4c2ko1a” but lots of ideas related to knowledge systems popped into my mind.
Don’t be distracted by my insane, paper-slips in physical-boxes system. There are countless ways to take notes. (Ahrens has a lot of great stuff to say about that, and I’d argue she has The stuff to say about it.) My point here is that by taking notes into a system that is designed to help me think—not tell me how to think—it does in fact help me think and helps me learn and remember.