I've had luck using a
hydraulic ram pump as an analogy with students with Mechanical backgrounds, but usually just drawing a simplified schematic works well. Just draw the FET, diode, inductor and capacitors. Replace the controller/feedback/etc with a magic box that emits a square wave. Then you only need to convince them of a few things:
0) Conservation of Power!
1) The inductor gives the electrons "inertia".
2) When the switch (FET) is conducting, electrons get to go to ground. They love that.
3) When the switch stops conducting, the electrons' "inertia" slams them through the check valve up into the high voltage side.
Usually I'll start with motor controllers, then buck regulators and then boost regulators. I find students have an easier time with that path, because they get used to the idea of being able to use the average of two states/modes if they toggle fast enough.
One word of warning - they all actually have three states they are averaging between, but I usually skip that part by assuming the toggling is fast enough. I gloss over discontinuous conduction until they are comfortable with continuous conduction or ask me about it. Continuous vs Discontinuous conduction is the biggest difference between a jaguar and a victor, so I try to time it coincident to them learning about victor compensation curves.