airborne - I've been teaching (different subjects) for a very long time, and often use "think of it as a....." suggestions to help with understanding.
I do, however, then enforce that with some means of remembering which is which, and why.
Apart from simply remembering (in which case you may as well remember the high/low answer anyway), how does your suggestion not get *some* people to say "Think of a low as a cushion, and a high as a 'hoover'".
Hoovers, indeed any brand of upright vacuum cleaner - and to that effect, most cylinder brands, are "higher" than cushions (well, taller).
I completely agree with your idea, I just like to know the "Why" behind many statements.