I think that a lot of things are better taught from the metal upward than the opposite. I had two course for networking the first taught me the layers top to bo

I think that a lot of things are better taught from the metal upward than the opposite. I had two course for networking the first taught me the layers top to bottom, I learned by hart the list of layers to pass the course but didn't understand it, the other was bottom to top and everything was clear then. Same thing with virtual functions, once I've learned how it was implemented then I was ready to understand why it was useful, not before.. It could be me who work this way, though.