The Magic Ring - Mobius Strip

Charles Kwan (ckwan@usa.net),(ckwan@dimacs.rutgers.edu)


General Information

The Problem
Discuss one sided surface figure and its applications in various fields.

Suggested Materials
adhesive tape

color pens

paper

ruler

scissors

Prerequisites
Pre-algebra

Activity Description

Guided Exploration
Define close curve, open curve, simple curve, complex curve, circumference, edge, perimeter, area, parallel lines, plane, topology, one-sided figure.

Have two students work in the group. Give each group one sheet of paper (8.5 by 11 or 8.5 by 14). Tell students to fold the paper into half(the long way, i.e. like the hot-dog). Cut the paper into two pieces. Fold each piece of paper into half (the long way). Cut both papers into half. Students should have four strips of band.

Have the students tape the two strips of paper together to form a long strip of band. Repeat this process with another set of bands.

On both strips of band, label each corner with different letters (i.e. A, B, C, D) in one direction and one side. Take one strip of paper ABCD and join it together without twisting the paper so A meets D and B meets C.

Have the students color the band with different colors for each side.

1. What kind of the curve is this?

2. How many edges does the band have?

3. How many sides does the ring have?

4. What is the circumference of the ring?

5. What is the surface area of the ring?

6. What is the area enclosed by the ring?

Have the students cut the ring along the center of the curve into half.

7. How many rings are there?

Students should be able to make some connections in finding the area and the circumference of a circle to finding the area and the perimeter of a rectangle.

Take a second strip of the band, twist one end of the strip and tape both ends together with A meeting C and B meeting D.

Have the students color the band with one color per each side.

1. How many colors are used to color the band?

2. How many edges does the band have?

3. How many sides does the ring have?

4. What kind of the curve is this?

Tell student the name of this strip is known as “Mobius strip or Mobius band or twisted cylinder”

Have the students cut along the center of the Mobius strip.

1. What kind of the curve is this?

2. How many twists are there in the ring?

Have the students cut the same Mobius strip again along the center of the band.

1. What have you discovered?

Concluding the Exploration
Discuss the practical applications of the Mobius strip.

A culminating assignment might include a research paper on how Mobius strip is used in arts, engineering and science. Also, encourage students to use the Internet as a resource for their research paper on the Mobius strip.

A Mathematical Approach
This hands-on activity is a good way to introduce students to different fields of mathematics, and geometry vocabulary. It also allows students to make connections among different topics in math and science.

Vocabulary:

close curve - no break in a line (continuous curve)

open curve - break in a line (discontinuous curve)

simple curve - the perimeter of a curve figure does not intersect (cross) itself

complex curve - the perimeter of a curve figure intersects (crosses) itself

circumference - distance around a circle

edge - a line segment on a space figure where two faces intersect

perimeter - the sum of the lengths of all sides

area - the region enclosed by the a plane figure

parallel lines - two lines in the same plane that do not intersect

plane - a set of points forming a flat surface that continues forever in all directions

topology - the study of the properties of figures that endure when the figures are subjected to continuous transformation

one sided figure - plane with one side only and vertices are joined by the opposite angles of a rectangle

Further Problems for Review or Assessment
1. Twisted both ends of the strip and joining them together.

a.) Do you have a Mobius strip?

b.) How many sides does the ring have?

2. Cut this strip along the center of the ring. What have you discovered?

Writing Assignment
1. What happens when a Mobius strip is cut parallel to its edge at a distance one third the width from the edge?

2. What are the applications of the Mobius strip or Mobius band?

3. How is Mobius strip and Mobius band used in arts?

Followup Problems or Activities
Annulus

Klein bottle

Torus

Read about the life and work of August Ferdinand Möbius.

Use WWW to explore related information for Mobius strip or Mobius band.

Math project or paper in topology

Topology Games

Teaching Notes

References
1. Bolt, Brian. “The Amazing Mathematical Arcade”, Cambridge University Press, 1984

2. Pappas, Theoni. “Fractals, Googols and Other Mathematical Tales”, Wide World Publishing, 1993

3. VanCleave’s, Janice. “Geometry for Every Kid”, John Wiley & Sons, 1994

4. Vorderman, Carol. “How Math Works”, Reader’s Digest, 1996

5. Henle, Michael. “A Combinatorial Introduction to Topology”, Dover, New York, 1979

6. Goodman-Strauss, Chaim. Workshop on Topology, Princeton University, June-July 1996

7. Garner, Jan. “The Mobius Strip”

8. Algebra Group WWW Server-August Ferdinand Möbius