Powers of Ten and Molecular Models

In this activity students go down the scale and are introduced to atoms and molecules, and the basics of states of matter. This may serve as their first acquaintance with the molecular underpinnings of chemistry. Equipped with this information, they are better able to understand their next investigation, the water cycle's evaporation and condensation, both important aspects of defining an ecosystem.

Activity: Up and Down the Scales (teacher)

Overview

Understanding scale is a fundamental science skill. Students will use Molecular Workbench software to get a visual sense of the relationship between objects of that size and a particular power of ten. In this day's activity, students undertake a Powers of Ten trip through the universe down to the level of molecules, in particular, the water molecule.

Goals and Objectives

The goal of the activity is that students will develop an intuitive understanding of the placement of objects such as the Solar System, their school and study site, a human being, cells and atoms on a relative scale. Students will be able to place on a relative scale a set of objects drawn from different places along a powers of ten scale.

(While young students need not fully grasp the exponential nature of distances involved, older students may be able to actually derive and graph an exponential from a lab experience. See Deriving the Exponential.)

Preparation

Have Molecular Workbench opened to the Powers of Ten activity on the class computer(s).

If double-clicking does not work, copy and paste this address into your browser:

http://mw2.concord.org/tmp.jnlp?address=http://mw2.concord.org/public/part2/ZoomIt/main.cml

Materials

Microscopes

5-6 meter sticks

Steps:

1. Working with microscopes: Look at a leaf under a microscope, if one is available. Have students record on the Powers of Ten student chart what they can see with the naked eye, then at 10x, 100x and any other available magnifications.

2. Working with meters: A meter is a unit that is within grasp, as is a fraction of a meter and roughly 5 times a meter. We will need to extend that understanding to give them a chance with the kind of scale relevant to atoms and molecules.

Ask students to select an object in the classroom that is one meter in length. They should use it, or meter long sticks to measure other objects in the room.

3. Have students then use

a.) the Molecular Workbench software

If double-clicking does not work, copy and paste this address into your browser:

http://mw2.concord.org/tmp.jnlp?address=http://mw2.concord.org/public/part2/ZoomIt/main.cml

and, if there is time, b.) the Eames web site to explore up and down through various magnifications.

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

Students should locate objects that they place on the following table:

Meter scale	Exponential	Examples
Nm	-9 (one billionth)
Microns (micrometer)	-6
Mm	-3
Cm (centimeter)	-2
M (meter)	-1
KM	+1

They should then asked to think of additional objects that should go in that "layer."

5. Assemble students in teams. Do the game in which various images from the Eames site need to be arranged in order.

http://www.powersof10.com/index.php?mod=nickelodeon

Other resources include:

http://micro.magnet.fsu.edu/optics/activities/teachers/perspectives.html

6. Powers of Ten GL Collection

Collect pictures of objects and submit them to their appropriate Power of Ten on the Global Lab Web Site. Please try to avoid submitting copyrighted images. Sources of free images include government agencies, e.g. NASA, and Wikipedia).

[ADD LINK FOR PICTURE SUBMISSION]

Title:

Browse for picture

Current Levels Available for Submission

(10) 12, 8, 7,6,5,4,3,2,1,0,-1,-2,-3,-4,-5,-6,-7,-8,-9,-10,-12

Description:

Test:

Match the object with the unit in which it is measured.

a skin cell	(mm)
a planet	(microns)
a virus	(thousands of kilometers)
a grain or small crystal of salt	(km)
city park	(cm)

Student Journal Reference: Metric Prefixes

		Multiplier
Prefix		Numerical	Exponential
yotta		1,000,000,000,000,000,000,000,000	10^24
zetta		1,000,000,000,000,000,000,000	10^21
exa		1,000,000,000,000,000,000	10^18
peta		1,000,000,000,000,000	10^15
tera		1,000,000,000,000	10^12
giga		1,000,000,000	10^9
mega		1,000,000	10^6
kilometer		1,000	10^3
hecto		100	10^2
deca		10	10^1
no prefix means:	1			10^0
Decimeter		0.1	10¯^1
Centimeter		0.01	10¯^2
Millimeter		0.001	10¯^3
Micro meter		0.000001	10¯^6
Nanometer		0.000000001	10¯^9
picometer		0.000000000001	10¯^12
femtometer		0.000000000000001	10¯^15
attometer		0.000000000000000001	10¯^18
zeptometer		0.000000000000000000001	10¯^21
yocto		0.000000000000000000000001	10¯^24