To some extent, it is reasonable for teachers to ask students to memorize some formulas, because the derivation process of these formulas is difficult for students with this education level, and it is difficult to draw this conclusion with existing knowledge, so they can only memorize them. Take the formula of circular area as an example, its derivation process generally involves knowledge such as limit and calculus, but for primary school students and junior high school students, it can only be memorized, because those knowledge will not be explained until high school and university. Therefore, for students in primary school, junior high school and even senior high school, what they learn is more focused on application, and they don't need to know how to get these formulas, but only need to know how to get the results in actual situations. This conforms to the principle of education.

Of course, this does not mean that all knowledge should be memorized. Students should also have certain logical reasoning ability, and some reasoning proofs within the scope of knowledge also need to be explored.