How do you explain density to a 4th grader?

Answer 1

Density is how much stuff is packed into a certain space. You can think of it like a sponge and a rock: the sponge is light and full of air, so it's less dense, while the rock is heavy and solid, making it more dense. If you have two objects that are the same size but one is heavier, that one has a higher density. It's like comparing a bag of feathers to a bag of stones—the stones are denser because they weigh more for the same amount of space!