The principle of conservation of energy is actually a very abstract concept. So it is amazing that we teach it to primary school kids. As a kid, I was taught that sound, light and electricity are all different forms of something called energy, which has this ability to morph from one form to another like a shape changer. It is also able to glide out of one body and slip into another, invisibly, like a ghost or spirit. I guess, as a kid, I didn’t have any problem accepting such a magical construct. Now that I am an adult, I realize that energy is a pretty bizarre idea. No one explains this better than Richard Feynman, in Section 4-1 What is Energy of the Feynman Lecture Series.
Spoiler: At the end of the analogy, Feynman dropped the profound punch line: “There are no blocks.” The idea that energy is never an actual thing really blew my mind.