Comment by khazhoux

> Once you understand maths there is a whole bunch that makes sense and you can just derive

(trigger warning: I'm going to use the word "privilege" and hate myself for it...)

The comment above is your math-brain privilege speaking. Not every kid has the required mathematical aptitude for that. You can reach a level of basic competency with repeated drilling and practice, but not everybody's brain is wired to be able to retain the conceptual foundations and then just derive the rest.

This is where math education has gone off the rails, at least in California. It's great to introduce and emphasize the "why", but the curriculum has completely abandoned repetitive drilling. Kids aren't building up any muscle memory.