On Vs Upon: What’s the Difference?

Knowing when to use on vs upon is a tough grammatical question, but I’ll straighten you out here.

Remember seventh grade, when your teacher stood at the front of the room and wrote various prepositions on the blackboard or whiteboard, expounding the difference between on vs upon? Perhaps they illustrated the point with a cat playing around a table, or a hiker exploring a mountain.

If that didn't stick with you, you're not alone. Prepositions are one of the most difficult parts of speech to...