Also...

You only need an apostrophe in "its" if you can successfully substitute the words "it is" in the sentence.

"The cat licked its butt."
"It's hotter than a mofo outside."

I really shouldn't have to be teaching you this at this age (unless you're in second grade).

P.S. If you're in second grade, how did you end up here?

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.