There are six books now. I had five at that time. However, derivatives should be told to senior three students, right? Where is your school? We are from PEP. I am a tutor. If we want to talk about derivatives, it is not impossible. Why don't you know who you are teaching? Not a teacher, right? Pay attention to the derivative: 1, where did the derivative come from? In fact, there are many classes of derivatives. I don't know if you want to say basic or application. Pay attention to the derivative: 1, the derivative, how it comes from the limit, this is going to be a lesson. There are more applications. Monotonicity and derivative, maximum and derivative, number and shape combination, each of which can be a lesson.

PS: Are you a teacher?