When we did ours it was "check the oil, check the tire pressure". It will honestly take up enough time and if they remember just that....then it's a win win.
Have a few different cars there, particularly a FWD economy car, a minivan/crossover, and a truck, because the engine layouts are all different, so the dip sticks will be in a different place. Some modern cars won't even have the dipstick, so you'll have to show them how to access the oil level screen on the display. Same with tire pressure.
Have them point out where the stuff is and have them check the oil. Same with manually checking tire pressures.
Then you are done.