From middle school onwards, it is a fact that mathematics becomes more difficult.
However, for the department in charge of education, there is no choice.
Someone once put forward this question: what should be done if one day the foundational disciplines develop to the point where humans need a lifetime to learn them?
Will the development of various basic sciences come to a halt? At least, judging from the current situation, the answer is obviously no!
The solution is probably to compress foundational knowledge, eliminate certain outdated knowledge points, and systematically move up the time for learning some concepts and theorems.
Every ten years or so, primary and secondary school curricula undergo significant changes. Outdated knowledge is discarded and replaced with more updated points.
The difficulty naturally rises steadily in this process.
And as the difficulty increases, the work of talent selection becomes increasingly stringent.
