Here’s a way to understand it better. You’ll need two sandwich size zip close bags and a big bag of cotton. Loosely fill the first bag with cotton. Count how many cotton balls you put in.

The bag is full of cotton, right?

Now, take a second bag, and put twice as many cotton balls into it.

It’s full of cotton, too.

Both of these bags are now full, but the second one is more densely packed than the first. It’s also heavier.

That’s what density is.

Now try this cool science project about the density of liquids. Take a jar, and add 1/2 cup oil, 1/2 cup water, and 1/2 cup syrup. Add them all at the same time. What happens? Oil is less dense than water. And syrup is more dense than water. As you can see.

There’s a lot more that you can discover about density. The concept of density can turn into a cool science project. Read about it at Watch This! Science Projects.