He's right, but it's also hard. He wants to be amazed, but being amazed also depends on your interest and level of knowledge at the time. And also the approach

He's right, but it's also hard. He wants to be amazed, but being amazed also depends on your interest and level of knowledge at the time. And also the approach and skill of the teacher. In my age I've learned that I'm a pretty bad teacher, and I can tell most people are really bad at it also. Even if you're a good teacher, in a class of 20, your approach will not be optimal for all: some will not understand, for some it will be too easy and boring, and for some it will be just right. His complaint about calculating the surface of a triangle is fair, but actually I do remember that in 5th/6th grade we had to derive things like the height of an even sided triangle give the length of the side, and subsequently the surface. But the Pythagorean theorem was kind of just given. Is there a way to provide a proof that children will understand and thus understand better in general? I think that's really non trivial (and I hope people are working on it).