I heard a new grammar error this week: A mother telling her son to “stop this instance.”

I empathized with her plight. We were in a crowded store. I wanted to get out of the chaos, and I’m sure she did too. Her son was focused on rearranging shelves of candy at the check-out line. You get the picture. That being said, what she meant to say was, “stop this instant.”

Do you know the difference?

The two words are closely related. Though “instant” can be an adjective, and “instance” can be a verb, we’ll be talking about both of them in their noun form today.

An “instance” is an example or single occurrence of something. An “instant” is a precise moment or very short space of time. Shall we practice?

Medical technology has advanced tremendously within the last 100 years. For instance, we now have a vaccine for polio. Jonas Sulk’s work in virology is one instance of a medical breakthrough.

We can see that, for our purposes here, “instance” and “example” can be used interchangeably.

As for “instant,” mentally replace the word “moment” until you feel like you get the distinction: Once you’re comfortable with math, the answers to simple problems like two plus two will come to you in an instant. Our sand castle was gone in an instant once the tide came in.

If you feel like you’ve got the hang of it, try this on for size: Sometimes ideas come to you in an instant; Archimedes’ famous “Eureka!” moment is one instance of this.

With a little practice, just like math, you’ll get the hang of when to use “instant” and when to use “instance.” If you really have trouble with it, just think of instant oatmeal: It only takes a moment to make.