What is density?

Density is how tight or loose things are packed together in a space.

Imagine you have two boxes, one full of marbles and one full of feathers. Both boxes are the same size, but the marble box feels much heavier because the marbles are denser, they take up less space but weigh more.

Think of density like a crowd at a party. If there are lots of people crammed into a small room, it’s very crowded, just like something that's dense. But if the same number of people spread out in a big hall, it feels much more empty, just like something that's less dense.

Now think about sand and air. A cup of sand is heavy because the grains are close together, they're denser than air, which you can't even see most of the time. That’s why when you fill a balloon with air, it floats, the air inside is less dense than the air around it!

So density is all about how much something weighs compared to how much space it takes up.