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Broken Bones

Grade Level: 8 (7-8)
Group Size: 4
Time Required: 3 hours

Summary: The purpose of this activity is to introduce students to the concept of the engineering design process and to teach them how to apply it. In “Broken Bones,” students will explore the steps of the engineering design process. They will first receive some background instruction about biomedical engineering or bioengineering. Then they will learn about material selection and material properties by using a guide created for them. Students will then break into small groups and brainstorm. Each student group is assigned a specific design problem. Students will be given materials and asked to create a prototype. To finish, students will communicate their solution through a poster presentation.

Engineering Connection: Biomedical engineers who specialize in biomaterials test and develop new materials that can be safely implanted in the body. Engineers who work in biomechanics apply principles from physics to biological systems. They develop artificial organs, such as the artificial heart. A strong background in Material Science is required to be able to design these these implants.

Materials List

– boxes to hold recyclable materials
– half can of Play-Doh
– 4 Popsicle sticks
– 6 to 8 recyclable materials: fabric, cotton batting, egg cartons, toilet paper or paper towel rolls, toothpicks, plastic bottles, milk cartons cut in pieces, rubber bands, straws, plastic tubing
– poster board
– markers
– digital scale


Explain to the students that there are many engineering disciplines. One of these disciplines is biomedical engineering or bioengineering. Biomedical engineers use their knowledge of math and science to solve health problems. Within the field of biomedical engineering there are many specialties. Using the “Introduction to Biomedical Engineering” handout as a guide (introduction.doc), give students some background information on the types of problems biomedical engineers help solve. Also go over the material properties worksheet. Now talk about the Engineering Design Process


bioengineering: a discipline of engineering that applies math and science to health problems.
prototype: a model or actual working version of a design concept.
material properties: factors that describe a material and how it will behave under certain conditions.
biomaterials: materials that can be safely implanted in the human body.
rehabilitation engineer: an engineer who improves the quality of life of people with disabilities.
tissue or cellular engineer: an engineer who develops cells outside of the body in order to create artificial tissues/organs with the same properties as the real body part.
genetic engineering: a bioengineering discipline in which an organism’s DNA is altered so that different proteins will be produced.


Hand out the worksheet.doc printouts.

Brainstorm in teams what the problem with the cast could be and how it can be solved. Each team will be required to construct a prototype that has a mass of less than 300 grams. Allow groups to brainstorm ideas for 20-25 minutes. Emphasize that in addition to solving the problem, the student’s design must be stable enough to hold the “broken bone” in place. Remind students that the materials in the box may represent any materials they would like, even ones that have not been developed yet. Students should be prepared to describe the properties of the materials they choose for their cast. In addition, each group may bring in one material from home.

Construct the Prototype: Students should use the materials provided and their sketches to construct a prototype cast.

Test and Evaluate the Solutions: Since the materials the students are using could feasibly represent any materials, the only physical test to determine whether or not the project is successful is measuring the mass of the students’ design. Allow students to use the digital scale to calculate the mass of their design. Students’ designs should be evaluated on their stability. Do they bend or move from side to side? Do they solve the problem given? In addition, students should design a test for their prototype that proves whether or not their problem has been solved.

Communicate the solution and Redesign:
A very important part of an engineer’s job is the ability to communicate ideas and solutions to a larger audience. Communicating the solution is step seven of the engineering design process. This communication may be with co-workers, superiors, or even customers. In this section of the activity, students will have the opportunity to communicate their solutions through a poster presentation. This is an important step in the process because it gives the students an opportunity to clearly articulate their design concepts. Remind students that good presentation skills are very necessary for a wide variety of professions. Teachers may decide whether they would like to give students the opportunity to redesign their casts based on feedback from the class.

Poster Presentation Development: Hand out the “Broken Bones Presentation Poster Content” worksheet. Students should create a poster that clearly explains their design. Posters should be neatly done and contain all required information. Students should be prepared to speak for 3-5 minutes on their design process and results. Classmates should be encouraged to ask questions.


Introduction to biomedical engineering (doc)
Introduction to biomedial engineering (pdf)
Worksheet (doc)
Worksheet (pdf)

Investigating Questions

-What is Biomedical Engineering or Bioengineering?
-What are material properties?


Evaluate students on the following criteria

-Sketch of prototype.
-Mass of the prototype.
-Stability of the prototype.
-Presentation style & content.
-Poster – Neat and detailed.

Owner: Center for Engineering Educational Outreach, Tufts University

Contributors: Connie Boyd, Terri Camesano, Emine Cagine, Angela Lamoureux, Hilary McCarthy, Robin Scarrell, Suzanne Sontgerath, Katherine Youmans, Tufts University

Copyright:  2005 by Worcester Polytechnic Institute
including copyrighted works of other educational institutions; all rights reserved.

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