As simple as a shoe might seem, it is actually a complex structure requiring a significant amount of engineering. Basically, a shoe is a system comprised of different parts that are sewn, stuck or welded together before being shaped and attached to a sole. In today’s world, thousands of different shoe designs exist and just as many engineers are developing new shoes and improving existing designs. When designing shoes, engineers consider all sorts of variables: suitable materials, anticipated forces the shoe will encounter, shoe wearer’s health and safety, as well as aesthetics (how it looks). Often, engineers work with podiatrists and kinesiologists (specialists in human movement) to design safe and comfortable shoes, and with fashion designers to create stylish and marketable products.Materials: For centuries, leather has been the primary material for shoes. However, due to the work of many engineers (especially materials and chemical engineers), we now fabricate shoes using synthetic (human-made) materials. Leather is still preferred by some shoe-wearers due to its comfort and durability. A limitation of leather is that it cannot be obtained in endless rolls, which makes it less suitable for factory production in the footwear, glove and upholstery industries. Also, the material properties of leather tend to change in different conditions, and it is susceptible to fungal infections.The main types of synthetic shoe soles that have been developed include materials based on ethylene vinyl acetate (EVA) and thermoplastic rubber. For the upper part of the shoe, polyurethane-coated fabric is a popular synthetic material. Polyurethane is a type of polymer that has many uses. It is commonly used as foam insulation in refrigerators and walls, packaging materials and upholstery. In the case of shoes, a very thin coating of polyurethane is applied to a cotton base. Polyurethane-coated fabrics have become increasingly popular because the surface creases closely simulate the ‘break’ or folding characteristics of leather. Also, its moisture absorption and permeability properties mimic natural leather. Polyurethane is water resistant yet breathable enough to discourage stinky feet!In this activity, students will use foam board for the soles.

(Images © 2007 Lauren Cooper, Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder.)

The soles of foam core shoes are relatively simple and can be created in a few steps:

1. Shaping the sole: Trace the shape of your feet on the foam core board and cut out the shape using an Xacto™ knife.

2. Fitting the shoe: Mark the lines at which the sole should bend to fit your foot and create hinges in the foam core.

3. Creating the lift: The heel and/or platform of the shoe requires more foam core design work, but a little creativity yields many designs! 
4. Design Considerations: The general performance requirements of a shoe include durability, high-abrasion resistance (less prone to scuffing), flexibility, dimensional stability (shoe does not shrink or spread in wear), resistance to chemical degradation, and good permeability and absorption properties.When designing a pair of heels or platforms, remember to design the toe box with enough room for the toes to assume a normal separation. Also, heels that are too wide do not necessarily offer more stability. In fact, heels with too much width can cause unhealthy side-to-side torque to the ankles, creating additional impact on the feet. The best design for a high-heel shoe is one with a narrower width, in which the heel is kept more solidly underneath the ankle. Lastly, make sure the heel is able to support the wearer! Make the heel flexible enough to absorb some shock, but rigid enough not to bend or buckle.

Materials

Each group needs:

• 1 utility knife/box cutter
• 1-2 markers (any color)
• 1 ruler
• assorted sizes of foam core board
• assorted decorating materials, such as ribbon, markers, paint, buttons, and construction paper
• hot glue gun/sticks
• duct tape (shared)
• 2 sheets of blank paper
• 1-2 pairs of scissors
• Foam Core Tips
• Fancy Feet Steps

Procedure

Overview: Students design and build high-heeled shoes using simple materials. They then test and redesign their shoes to provide maximum comfort and stability for the wearer.

Image: Michael Jackson’s Anti-Gravity Illusion Shoes Patent Drawings 

Before the Activity

• Review background information, including how to create shapes with foam core. Building a pair of foam core shoes for demonstration is a good way to practice with the material.
• Gather supplies and make copies of the Foam Core Tips and Fancy Feet Steps, and/or prepare overhead transparencies of them.
• Prepare a classroom or hallway area suitable for a “walk-off” to take place at the activity conclusion. One suggestion is to have the walk-off in an area in which students from other classes can watch the activity to see how cool it is be an engineer!

With the students

1. Organize the students into groups of two or three.
2. Give each team a copy of the steps and tips handouts.
3. In their groups, have students discuss for 3-4 minutes the properties that make up a good shoe (that is, flexible, comfortable, stylish, durable, etc.). Then, lead a brief class discussion on the same topic, specifically discussing stability, what the shoe will be used for, how durable it needs to be, its comfort, etc.
4. Tell students that they will be making high-heeled shoes from the materials listed above (show supplies to students). They need to make a pair of shoes to fit one member of their team, then that member will complete a “shoe walk” through an obstacle course.
5. Give each team a half sheet of foam core board. Explain the engineering design challenge: To create a prototype of a heeled or platform shoe design using only a half sheet of foam core. The finished product should be a pair of shoes that can support the student’s weight while walking. As an example, show students a finished pair of foam core shoes.
6. Have student groups brainstorm ideas for their shoes (10 minutes), sketching out viable ideas on paper. The shoes should meet the following requirements: At least a two-inch heel (at the highest point); Must stay on the foot without being held on by the other foot or a hand; Must be a matching pair (left foot and right foot).
7. As necessary, demonstrate how to create different designs using the foam core techniques described in the tips handout.
8. Review the safety hazards of using Xacto™ knives and glue guns.
9. Have each team generate several preliminary sketches of possible shoe designs. Remind students to recall the ideas they generated earlier.
10. Lead the activity embedded assessment (see Assessment section) in which each team swaps its favorite preliminary sketch with another team and provides constructive feedback.
11. After each group has agreed on a shoe design, have students check their ideas with a leader before they begin building. Make sure they have a plan for making the shoe fit, holding it on, making sure it is the right size, keeping the heel attached, etc. Give them time to figure out how they will cut all of their shoe components efficiently from the half sheet of foam core board. Allow about 15 minutes for building.
12. Please note: for the next step, the instructor(s) should supervise the use of the hot glue guns and utility knives at all times. If necessary, cut/glue the material for students. 
13. Help students safely cut their shoe components from the foam core using the knives.
14. Help students glue shoe components together using the hot glue guns.
15. Advise students to test and modify their shoes before decorating and finishing them.
16. If some students’ shoes are buckling or failing when tested, help them brainstorm possible solutions. See the Troubleshooting Tips section.
17. To complete the design/build portion of the activity, give students time to decorate their shoes and prepare for the “walk-off.”
18. Conclude the activity by leading the class in a “walk-off” around a short obstacle course to see which shoes hold up best. (Allow 5 to 7 minutes for the test.)

7. After the obstacle course is completed by all groups, give students a chance to improve their shoe designs, addressing any flaws they noticed in the testing. As time permits, have students continue to test their shoes as they see fit.

Wrap Up – Thought Questions

• Which aspects of your design worked well? Why?
• Which aspect did not work well? Why not?
• What other supplies could you have used to build your shoes? How would you have used these additional materials?

Activity Scaling

For older students: 

Encourage them to create more complicated shoe designs. Assign each team to design a pair of shoes that performs a specific function. For example, “Wrangler” shoes might be similar to cowboy boots. “Summit” shoes might be designed for hikers. “Puddle Jumper” shoes might be waterproof. Provide students with a greater variety of materials (such as cardboard, foam, foil, plastic wrap, cork, etc.) from which to create these “functional” shoes. Have students discuss the compressive and tension forces in action with their shoes.

• Convertible Shoes: Function, Fashion & Design, Form – Teams of high school students apply their knowledge about the mechanics of walking and running to design and build shoe prototypes that convert between high heels and athletic shoes.

For younger students:

Prepare foam core shoe components in advance. Give each group a different set of shapes and have them create their shoes without using the sharp knives.

• Engineer a Sneaker Students in 4th and 5th grade decide on specific design requirements, such as good traction or deep cushioning, and then use a variety of materials to build prototype shoes that meet the design criteria.

Additional Resources

Day in the Life of a Shoe Designer. ConnectEd’s “Day in the Life” series focuses on Shane and Fabio Rattazzi, founders of DZR shoes who specialize in producing functional and fashionable cycling shoes. [YouTube 4:43]

Secrets of Shoe Design. England’s Victoria and Albert Museum interviews famous shoe designers about the source of their design inspirations and their craft. [YouTube 13:01]

How to Use 3-D Shoe Design Software. AutoDesk webinar explaining how to use design software to cut the time and cost of taking concept shoes to market. [YouTube 33:51]

The Engineering Behind Shoe Design.Great information about engineering in everyday life at the University of Southern California’s Viterbi School of Engineering’s online magazine, illumin. 

Walking in High Heels, the Physics Behind the Physique. Another Illumin article.

Summer Academy Connects Girls to STEM Possibilities. West Virginia University’s 2015 summer program included a shoe design contest.

Science and Engineering Camp Aims for Girls. Charleston (W.Va.) Gazette-Mail article (July 1, 2015) on shoe design challenge at West Virginia University Institute of Technology’s STEM Summer Academy for girls.

Photo by CRAIG CUNNINGHAM/DAILY MAIL

Copyright © 2007 by Regents of the University of Colorado