I'd like to teach the English-speaking world something

The word "is" is a verb. If you have a title or a caption or a whatever in which you are capitalizing other non-prepositions, you need to capitalize "is" as well. I know it's a cute little word and all, but it's a vital one. I can't tell you how often I run across this unforgivable error, especially lately, and I've just had enough.