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### How do the sizes of small things compare to one another?

#### Purpose

We've been exploring different worlds: micro, nano, and atomic/molecular. If you could shrink down to a size where you could be on the same scale as objects that live in these worlds, what would you see?  Imagine you could shrink to 50,000 times smaller than you are now and are walking through a groove on the edges of a dime.  What other objects could you see in that tiny space?  How would you compare to bacteria?  And how would a bacterium compare to DNA or a water molecule? Let's take a trip along the groove of a dime and take some mental pictures!

#### Overview

Let's do some exploring! What kinds of objects live in the micro world? The nano world? How about the atomic or molecular world? Think about how popular media has attempted to manipulate size:remember examples of Horton and the Who, Honey, I Shrunk the Kds, Men in Black?  Find object from each of these worlds and follow the steps in the presentations. Your objects will be part of our trip along the groove of the dime.

#### Investigate

1. Look at the big model of the dime.  If you shrunk yourself 100x, you would be about the size of this dime. You are now in the millimeter world!
2. Follow the presentation above and be prepared to shrink another 500x (for a total shrink of 50,000x) for your trip across the groove of a dime.
3. Take the guided tour across the edget of the dime .
4. Upon returning to the classroom (and human scale) look at the edge of a real dime with their magnifying glasses. As you view an actual
dime, think back to the journey across the thickness of a dime and the objects you encountered along the way.

#### Why this works

It is easier to understand relative scale (comparing the size of objects to you or a shrunken you) than an absolute scale (comparing the size of objects to each other without a reference point). As you went on the dime walk, you gained an authentic perspective of how the sizes of different objects compared with you if you were 50,000 times smaller than you are. Even if you were 50,000 times smaller and walked on the edge of a dime, you couldn't see an object that is one nanometer in diameter.

#### Wrap Up

Imagine your journey across the groove of a dime and the "worlds" through which you traveled. When you took the dime walk, which objects did you see so far that live in that world? Discuss with a partner the names of some of the objects in the nano world. Feel free to review the size line in the NanoScale Me interactive.

What substance is essential for every living thing, but also might have living things in it?  If you thought of water, you are right! What else might be in water?  Write or draw in your notebook every possible source of water and identify everything you can think of that might be in it.  Do you think you can see everything?  As you consider these questions, imagine that you are on the dime walk again. Where would all of these things be placed?

#### Materials

• Dime Walk images (working on modifying and cleaning up/formatting images for dw. objects that are in water filtration lesson will be included)
• Oversized dime slipcover with edges
• Child’s inflatable pool (4’ diameter)
• Pump kit to inflate pool
• Lego™ people, Meeples, or other small figurines that are approximately as tall as a dime
• Hand lens
• Dime (for each student)

• n/a

#### Based on

• Tom Tretter and his colleagues (2006)
• Original work by McREL