Set Theory

You’ve been teaching your kindergarten class about subtraction. You have a whole class discussion about why 5 apples minus 3 apples is 2 apples. You even bring out apples to demonstrate. One student looks up at you, all excited and curious, and asks, “What is 5 apples minus 3 bananas?” Another student says, “It’s 5 apples and 3 bananas.” Another student says, “No, it’s 2 apples.” Now everyone is getting confused! Can you help them?