An instance is a single example or case of something. When your teacher says “I need three instances where the character showed bravery,” she wants you to find three separate moments in the story where bravery happened. Each time the character did something brave counts as one instance.

Think of an instance as one specific occurrence. If you forgot your homework once, that's one instance of forgetting. If you forgot it five times, those are five separate instances. Each individual time something happens is its own instance.

Scientists use the word this way too. A doctor might say “This is the first instance of this disease appearing in our city,” meaning the first time it's shown up there. A weather forecaster tracking tornadoes counts each tornado as a separate instance.

You'll sometimes hear people say “for instance” when they're about to give an example: “Many animals can camouflage themselves; for instance, chameleons change color to blend into their surroundings.” That phrase means “here's one example of what I'm talking about.”

The word helps us be precise when we're counting or describing how often something happens, separating individual examples from the general pattern.