Supermemo is a learning system that uses spaced repetition to seal knowledge in memory. Not long ago  I wrote about the inventor, Piotr Wozniak, for this story about Supermemo in Wired. (It has since been collected in The Best American Science Writing, 2009.)

This story counts as one of my favorites, for three reasons. First, I owe to it my friendship with Wozniak. Although he does not travel and I have not yet been back to the northern coast of Poland where he lives, we remain in close contact, and I find that I’ve been deeply influenced by his unusual – some might say eccentric – point of view. He is an extreme rationalist, and a very happy and productive person. Second, I associate this story with the fact that, after a 40 years of  being monolingual, I learned Spanish using Supermemo. Although my Spanish contains many errors, it is serviceable enough for conversation on almost any topic with a sympathetic listener. After many other attempts, I finally made it up onto that first, hardest step in learning any language: getting enough loaded into memory to permit meaningful and wide-ranging communication. As for fluency, this will take a lifetime. But it is now a lot more fun. To stand at the edge of a nearly limitless language-culture is exciting. There are treasures everywhere.

The final reason the Wozniak story remains on my mind is that it left me with a difficult problem that I enjoy continuing to try to solve. Why isn’t this amazing technique more common? I explained some of the obvious reasons in my story. Still, I expected that, having launched the idea into an environment well suited to nourish it (many Wired readers are passionate learners, and many of them have software, design, and business skills), I would soon see some new implementations. And I was not disappointed. There are half a dozen versions of Supermemo in common use today. But they are used by very few people. Clearly, the problem remains unsolved.

I still think about this quite a lot. If you are a Supermemo user, I would like to hear from you.