*Learning Themes:* 1 | 2 | 3 | Glossary |

**Quarks are the smallest things that everything is made of, but how small are they?** The theory of particle physics says that quarks are pointlike and have no size. Because science relies on observations and measurements, we can only say that quarks are less than 10^{-18} meters in diameter. This is the same as 0.000000000000000001 meters.

#### Games and Activities

#### How small can you cut?

HTML | Printable PDF | Grades 1-5

What are the smallest things we know of, and just how small are they? This lesson explores how small quarks, the smallest thing we know of, are by cutting paper and relating this to everyday objects.

Printable student worksheet PDF

#### Pea brain! Explorations in Estimation

HTML | Printable PDF | Grades 4–8

Use two different techniques to estimate how many little things fit into a bigger thing.

Printable student worksheet PDF

#### Where will it go?

HTML | Printable PDF | Grades 1-4

Make a prediction of where a ball will go after it bounces off an object.

#### What shape is it?

HTML | Printable PDF | Grades 4-8

Can you guess what shape an unseen object is? By bouncing a ball off the object, can you guess something about it?

#### Invisible Investigations

HTML | Printable PDF | Grades 4-8

Using indirect observational methods, you can distinguish between charged and uncharged objects.

Printable student worksheet PDF