NanoSurvey‎ > ‎

### How do we measure "small" using the metric system?

#### Purpose

In America, we measure length, height, and distance using units such as inches, feet, and miles. That works in the macro scale, the scale of our day-to-day lives. However, when you want to measure something vast, like the distance between Earth and the Moon, or something tiny, like the width of a DNA molecule, we use a world-wide language called the metric system, with measurements based on meters (kilometers, millimeters, nanometers).

Let's explore the metric system, a "base ten" system, and look for patterns that will ground us all the way to the nanoscale.

#### Overview

Experiences at the macroscale - the scale of meters and centimeters and milimeters (basketball players and ants) - can help us conceptualize (develop a concept for) far smaller worlds, where blood cells and bacteria and DNA and water molecules flourish - the micro, nano, and pico worlds!

#### Investigate

1. Find a couple of team partners and go through the activity in the PowerPoint above.
2. Webquest
• Consider one of the largest and one of the smallest objects you have seen.
• Look up the length of each, sketch a picture, and write down its length using the metric system.
3. Compare the objects. Are they in the same units (meters? millimeters? kilometers?)?
• Challenge: how many times bigger is the length of the larger object than the length of the smaller one?
4. If you have time, compare your objects to the objects of other individuals or small groups and see if you can determine the smallest and largest objects based on their lengths and their metric measurements.

#### Why this works

Creating models that not only represent size and scale and corresponding numbers, but that also explain the logic behind the metric system, builds background knowledge for understanding measurement in science.

#### Wrap Up

What real objects could represent the power of ten? For example, a human hair could be the benchmark for .0001 m or a tenth of a millimeter, close to as small as we can perceive with the naked eye. Begin developing class benchmarks for each size. The next activites will give you more ideas.

#### Extensions

• Make you own measuring system, starting with your own unit.                  Ex. My unit is a red ant. That flower petal is 8 ants wide.

#### Based on

• McREL original work