A difficult topic in middle school is function, specifically X, and then the function image with coordinate system. This topic is generally quite unsolvable during middle school, because there is no formula in high school, and there is almost only one idea for this topic, so students can hardly find the idea, so this is more difficult.
For example, the last question, to prove congruence or the relationship between various angles, for example, to put two triangles on the image of a quadratic function, and then to prove congruence, similarity, angle size or function formula of various straight lines, and to prove the various relationships after the triangle moves to form a shape ... quite tangled, but as long as time is enough, this problem can be figured out.
About X, this idea is vicious, but once this kind of question is raised in middle school, people will feel very complicated and dare not start, and then after a little analysis, they will find that it is actually nothing and the real difficulty is not great.
The difficulty of middle school topics is real to me as a college student ... but I remember it was still very challenging at that time. Do not give up.