Comment by wongarsu

We don't have enough time to derive everything from first principles, but we do have the time to go over how something was derived, or how something works.

A common issue when trying this is trying to teach all layers at the same level of detail. But this really isn't necessary. You need to know the equation for Ohms law, but you can give very handwavy explanations for the underlying causes. For example: why do thicker wires have less resistance? Electricity is the movement of electrons, more cross section means more electrons can move, like having more lanes on a highway. Why does copper have less resistance than aluminum? Copper has an electron that isn't bound as tightly to the atom. How does electricity know which path has the least resistance? It doesn't, it starts flowing down all paths equally at a significant fraction of the speed of light, then quickly settles in a steady state described by Ohm's law. Reserve the equations and numbers for the layers that matter, but having a rough understanding of what's happening on the layer below makes it easier to understand the layer you care about, and makes it easier to know when that understanding will break down (because all of science and engineering are approximations with limited applicability)