Why did the teacher wear sunglasses?
Because her students were so bright!
Bright Students
Explanation
Explain Bear
Alright, listen up, buttercup. The teacher put on sunglasses 'cause her students were "bright," get it? It's a play on words. "Bright" can mean smart, or it can mean shining, like the sun. You probably need sunglasses too since you are dumb as a rock.