MYSTERY NAME  (Teflon Tape)

INTRODUCTION

This activity is appropriate for intermediate elementary school children in grades 4-6 to introduce the properties of polymers.   We often use it under the guise of getting to know the names of certain students.


PURPOSE

The purpose of this activity is to introduce children to various properties of polymers, in particular a property of stretch that changes depending on the direction in which the tape is pulled.  This activity also illustrates the variety of properties that can be intentionally built into a polymer when it is made initially.
 

MATERIALS
 

1  roll of plumber's Teflon tape (1/2-inch width is most common, but 3/4-inch width or even 1-inch width is preferable even if you have to order it at a local hardware store)

1  black or dark-colored marking pen (black or dark blue Vis-a-Vis overhead projector pens or  black or dark blue SANFORD Sharpie permanent markers work well)

1  roll of 1/2-inch width masking tape
 

PREPARATION FOR THE ACTIVITY

Unroll 2 - 4 inches of Teflon tape, the length depending on the length of the name or message to be printed on it later.  While someone else holds the tape on a flat surface, place a strip of masking tape across each end and around both sides of the Teflon tape to provide for easy and even stretching of the length of Teflon tape later.

PROCEDURE

1. Ask the class who has a name or nickname with only three or four letters.

2. Pick a child, and tell that child that you will figure out what the name or nickname is.

3. Give the child the piece of Teflon tape.

4. Tell the child to use the marking pen and print the name or nickname in large capital letters on the Teflon tape while a second child is holding the Teflon tape firmly on a flat surface around where the first child is printing.

5. Have the first child grab the top and bottom of the Teflon tape (as versus the ends of the tape) with thumbs and forefingers, and stretch the Teflon tape slowly and gently out to an inch or more.  Tell the first child to describe to and show the class, but not you, what is happening.

6. Tell the first child to repeat the stretching process at a couple of other points along the length of the Teflon tape.

7. Then tell the first child to hand the jumbled, unreadable Teflon tape to you, right-side up.

8. Grab the Teflon tape by the ends (on the masking tape), and stretch it slowly but firmly out to its original length.  The Teflon tape takes on its original shape before stretching by the first student, and the name or message is easily read.

EXPLANATION

See Polymer Game to learn about the nature of polymers.  Teflon is a trade name for a waxy, opaque, polymeric material called polytetrafluoroethylene.  Teflon was discovered in 1938, but was not found useful in non-stick cookware or as Teflon tape until more than 20 years later.  In the Teflon tape the polymer chains are already stretched significantly like straight strands of uncooked spaghetti.  However, the chains are only weakly bonded between chains to each other, and when stretched across the tape, become more like jumbled cooked spaghetti on a plate.  Pulling on the ends of the chains (pulling at the masking tape) stretches the chains back to their full length and draws the Teflon tape into its original shape.  The name or message can then be read easily.

If you need to stop a leak in plumbing in your bathroom or kitchen by wrapping Teflon tape around the threads to seal a joint between two pipes or fittings, you will see that these properties of stretching easily in one dimension but not in the other is very important in using the Teflon tape to stretch over threads and seal valleys between threads.  A teacher or parent can illustrate this.

ADDITIONAL SUGGESTIONS

Teachers should try this activity several times before using it in the classroom to get the feel of it and to be able to make suggestions to students.