I've been reading a lot around this "spaced repetition" movement over the years and also tried it out sometimes myself. However, I'm still kinda a bit confused about this supposedly big "rote memorization I learnt in school" vs "spaced repetition which is what we should be using" distinction which is always brought up.

Don't treat this comment as I'm skeptical to spaced repetition or its scientific claim. I think it's great that it's being brought up so that more people can try it out! But these articles tend to always paint this picture of the current educational system being archaic as if nothing has improved in last ~50 years.

> During the school years, most of us got used to spending hours at a time memorizing facts, equations, the names of the elements, French verbs, dates of key historical events. We found ourselves frantically cramming the night before a test. We probably read through our notes over and over, a gallon of coffee in hand, in the hope that the information would somehow lodge in our brains. Once the test was over, we doubtless forgot everything straight away.

This doesn't really match how I was taught. I wasn't given a list of Spanish (the third language I learnt in school) verbs to memorize. Instead each chapter started with a set of new words we were supposed to learn, and then we did a bunch of reading/writing/listening exercises where we used these words over the next few days/weeks. During the week we slowly started internalizing them and we didn't stress if we didn't knew them by heart from the first day. In the following chapters they would repeatedly bring back previously learnt words. Everyone knew that you would have to both do weekly exercises to stay on top, and then later on repeat if you wanted for it to stick.

Of course, in practice, I often ended up having to panically memorize something before a test, but this had nothing to do with me thinking this was "the best way to learn". This was because I didn't actually cared about the topic, did tons of other cool stuff instead of learning it, and still wanted to put in some effort to get a decent grade. I certainly wouldn't blame my teachers for the "rote memorization" I put myself under. They constantly told me that it was much better to learn slow and steady during the semester and build up understanding of the topic.

> We don’t learn about spaced repetition in school—something which baffles many researchers.

The concept of "spaced repetition" is in my opinion well-understood by most people. Everyone expects that you need to repeat in order to learn.

As for the elaborate system of spaced repetition where you're precisely tracking everything to optimize for retention: Which researches are "baffled" that we're not learning this in school? It's something which hasn't been practical at all until very recent times (with phones/computers), and I'd expect that most researches on learning understands that teaching in school is a multi-faceted problem and that "this one trick" isn't the magic solution to all of our educational problems.

> Most classes teach a single topic per session, then don’t repeat it until the test.

This is not my experience at all. In History we were always asked to compare what we learnt in different chapters. Most of Maths typically build on top of each other, and e.g. you will end up practicing basic arithmetic when you're solving quadratic equations. It felt like teachers spent a lot of time to think about how to structure the curriculum so that we had a cohesive learning experience. And often they explicitly called out when we switched to a completely different part of the curriculum. It was also pretty common to have "summary" lecture at the end of these parts.

> A typical spaced repetition system includes these [four] key components

Trust me: I was often struggling to motivate myself to even pay attention to the topics. Having this elaborate system I had to maintain would not helped me in school at all.