Education and Outreach: Nanotechnology Activity Guides

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Cutting it Down to Nano

Audience: General public; any science or math class (with modifications)
Time Needed: 5-10 minutes (20-25 minutes for a revised classroom activity)

Objectives:

• Understand the smallness of the nanoscale
• Appreciate the impossibility of creating nanoscale materials with macro scale objects
• Understand the invisibility of the nanoscale to the unaided eye

Related Wisconsin Model Academic Science Standards:

• C.4.2 Use the science content being learned to ask questions, plan investigations, make observations, make predictions, and offer explanations
• C.4.4 Use simple science equipment safely and effectively, including rulers, balances, graduated cylinders, hand lenses, thermometers, and computers, to collect data relevant to questions and investigations
• C.4.5 Use data they have collected to develop explanations and answer questions generated by investigations
• C.4.6 Communicate the results of their investigations in ways their audiences will understand by using charts, graphs, drawings, written descriptions, and various other means, to display their answers
• C.4.8 Ask additional questions that might help focus or further an investigation

Activity Materials:

• Scissors
• Tape
• A strip of paper (dimensions 216mm x 5mm)
• Pen or pencil
• Ruler
• Calculator

Activity Instructions:

The challenge of this activity is to determine the number of times the student needs to cut the strip of paper in half in order to make it between zero and ten nanometers long.

As a Table-Top Demo

Explain to the student that "nano" means one billionth and that a nanometer is one billionth of a meter. If necessary, remind her that a centimeter is one hundredth of a meter and millimeter is one thousandth.

Give the student the 216mm x 5mm piece of paper, the Cutting it Down to Nano worksheet, and a scissors. Tell the student what the paper’s dimensions are. Mention that she also has a calculator, a ruler, and the worksheet to use if she wants them.

Ask the student to guess how many times she has to cut the paper to make a 10 nanometer-long piece. Ask her how many times she thinks she can cut the paper before it becomes impossible to cut.

Tell the student to cut the paper in half as many times as she can. After each cut, have her tape one half to the worksheet and reserve the half for further cutting. This will allow her to keep track of the number of cuts she makes.

Once she has completed the activity, discuss the following questions with her:

• Were her predictions to the above two questions accurate? (It takes 26 cuts to make a 10nm-long piece.)
• How many times was she able to cut the paper?
• How close was the smallest piece to the nanoscale?
• What sort of curve is formed by the cut pieces of paper taped to her worksheet?
• Why did she have to stop cutting?
• Can macroscale objects, like scissors, be used on the nanoscale?
• Can she think of any way to cut the paper any smaller?

As a closing point, emphasize that the demonstration shows how small nano really is and how inadequate macro scale tools, i.e. the scissors, are in dealing with the nanoscale.

As a Classroom Activity

Introduction (3-5 minutes)
Explain to the students that nano means one billionth and that a nanometer is one billionth of a meter. If necessary, remind them that a centimeter is one hundredth of a meter, a millimeter is one thousandth, and a micron is one millionth. Show the students the strip of paper and tell them what its dimensions are. Explain to them that the challenge is to cut the piece of paper in half repeatedly in order to make it 10nm long.

Activity (10 minutes)
Have the students get in pairs and give each pair the ruler, calculator, scissors, pen/pencil (if necessary), strip of paper, and accompanying worksheet. Remind them to answer the first two questions on the worksheet before they begin cutting. Tell them they have 10 minutes to complete the activity.

Discussion (5-10 minutes)
After 10 minutes (or earlier if they are done), discuss the activity, focusing on the following questions related to their worksheets:

• Were their predictions to the above two questions accurate?
• How many times were they able to cut the paper?

Have the students look at the worksheet with the measurement table. Briefly discuss the size of some of the objects. Discuss the following questions:

• How small could they get their paper, and how small were the corresponding objects?
• How close was their smallest piece to the nanoscale?
• Why did they have to stop cutting?
• What does that say about using macro scale objects, like scissors, to deal with things on the nanoscale?
• Can they think of any way to cut the paper any smaller? (Answers could include using a microscope or smaller scissors.)

Modification Options

For younger audiences or for groups who find scientific notation and/or measuring difficult, you could concentrate only the "objects on that scale" portion of the measurement table.

Students could create their own measurement table. Ask them to measure and record the length of each successive piece of paper in millimeters. They could also rewrite the measurements in scientific notation. If desired, students who understand scientific notation could be paired with those who do not. Have the former guide the latter through the activity.

Required Background Information:

For this activity, students need to be comfortable, the metric system (millimeters and smaller), and measuring. If doing one of the modified versions, students should also be familiar with scientific notation. If necessary, review scientific notation and other related concepts:

• Prefixes: deci- (1/10th), centi- (1/100th), milli- (1/1000th), micro- (1/1,000,000th), nano- (1/1,000,000,000th)

• Scientific notation is a shorthand way to write numbers that are very large or very small by using powers of ten (exponents)

• If a number is 10 or greater, then the decimal point is moved to the left until only one numeral, or significant figure, remains to the left of the decimal. For example, 1,000,000 meters is shortened to 1 x 106 meters. Similarly, 4.5 x 104 is 45,000

• The exponent represents the number of places the decimal was moved

• If a number is less than one, then the decimal point is moved to the right until one significant figure is to the left of the decimal. For example, 0.000001 meter would be shortened to 1 x 10-6 meter. Similarly, 6.7 x 10-3 is 0.0067

• Again, the exponent represents the number of places the decimal was moved. However, the addition of the negative sign indicates that the decimal was moved to the right and that the number is less than one

Supplemental Materials:

• Handout: Cutting it Down to Nano Worksheet (pdf)
• Handout: Calculation Worksheet (pdf)

References:

• MRSEC - http://mrsec.wisc.edu/edetc/

Authors:
IPSE Interns: Julia Bickler, Wendy deProphetis, Manisha Ghorai, LJ Janowski, Ed Kabara, Nancy Karuri, Yvonne Kao, Laura Kopplin, Melissa Kurth, Lauren Sammel, Erin Schmidt, Naveen Varma

IPSE Leadership Team: Wendy C. Crone, Amy Payne, Greta Zenner, and Tom Derenne

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The Nanotechnology Activity Guides are a product of the Materials Research Science and Engineering Center and the Internships in Public Science Education Project of the University of Wisconsin - Madison. Funding provided by the National Science Foundation.