I have kept some of my old school books and have recently -- for reasons
that might deserve their own phlog post some day -- read a bit through
them again. Specifically math books.

What struck me as very odd was the style of those math books: They
contain very, very little explanations. They feel more like references.
If you were to put them on a scale, I'd say:

      My books
          |
          v
    |-----x-------------------------------|
    Pure                               Full
    Reference                  Explanations

I'm talking about things like linear algebra, stochastic, analysis, ...

As a consequence, you can't just take these books, read them, and learn.
You won't understand a thing.

My time in school is long over and I don't really remember anymore how
this worked. But judging by these books, I guess that our teacher
explained a certain topic and then we'd get some homework -- the
excercises came from those books. In other words, you had absolutely no
way of re-iterating the stuff you did at school, re-read it again, try
to understand it again. Either you got it when the teacher explained it
or you didn't. End of story.

How odd?

Why not have books that *explain* the topics, so I can read up on them
again?

This model means that the teacher had to do a lot of the heavy lifting.
If he/she was bad explaining a topic, that's *your* problem. Or if you
were sick for a week. Or if the other kids were noisy. Or a million
other reasons.

(These days, you have The Internet to look things up, but that wasn't an
option during my school days.)

I wonder how math classes are these days.