What does it truly mean to understand something?
When you are reading a concept , for example ,you are learning Integration, you build a mental model of it in your head and you feel like you understand it . But on the back of your head , the whole structure of the concept looks very complicated and hard to remember. But, you don't feel the same way for basic concepts such as motion ,force ,velocity. You don't really have to try to remember it . It is just there present in your head . You can derive it in any forms you would like to . It necessarily implies that you truly understood it. I suppose that if you truly understand something , there will be no form of struggle to structure the concept in your head. You can derive it in any forms.