It's easy to tell if a building is very tall--just look up! But what about how big a building is? Big buildings are more than just tall. They are fat, too.

Big buildings are important because they can hold a lot of people, just like a big fat cup that holds more water than a tall skinny glass.

To know how big a building is, you have to measure three things. First, you find out how wide it is. How far is it from the left side of the building to the right side? Then, you see how deep it is. How far is it from the front of the building to the back? Now, you find out the height of the building. How far is it from the ground to the top of the building?

We call these big buildings "Jumbo." Click here to see what we mean.