Hands-on Activity: Broken Bones & Biomedical Materials

Contributed by: Center for Engineering Educational Outreach, Tufts University

Quick Look

Grade Level: 8 (7-8)

Time Required: 3 hours

(Time can be reduced by assigning research of the problem as homework and eliminating any redesign time)

Expendable Cost/Group: US $3.00

($20 per class)

Group Size: 4

Activity Dependency: None

Subject Areas: Science and Technology

A man's broken arm placed in a blue and orange cast.
Students design to improve a cast for a broken arm
Copyright © Wikimedia Commons http://upload.wikimedia.org/wikipedia/commons/9/9b/Day_220_-_My_Husband's_Cast.jpg


Students are introduced to the concept and steps of the engineering design process and taught how to apply it. Students first receive some background information about biomedical engineering (aka bioengineering). Then they learn about material selection and material properties by using a provided guide. In small groups, students learn of their design challenge (improve a cast for a broken arm), brainstorm solutions, are given materials and create prototypes. To finish, teams communicate their design solutions through class poster presentations.
This engineering curriculum meets Next Generation Science Standards (NGSS).

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 implants.

Learning Objectives

The purpose of this activity is to introduce students to the concepts of the engineering design process and teach them how to apply those steps to an engineering design challenge. In this activity, students:

  • Learn about different engineering disciplines.
  • Use the engineering design process to solve a specific design task.
  • Learn how to evaluate and choose materials based on material properties.
  • Explore the concept of a prototype.
  • Sketch and build a prototype of a design including a cross-section view.
  • Explore the field of biomedical engineering.
  • Develop methods for communicating a design solution to a group.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS Performance Expectation

Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions. (Grades 6 - 8 ) More Details

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This Performance Expectation focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Define a design problem that can be solved through the development of an object, tool, process or system and includes multiple criteria and constraints, including scientific knowledge that may limit possible solutions.

Alignment agreement:

The more precisely a design task's criteria and constraints can be defined, the more likely it is that the designed solution will be successful. Specification of constraints includes consideration of scientific principles and other relevant knowledge that is likely to limit possible solutions.

Alignment agreement:

All human activity draws on natural resources and has both short and long-term consequences, positive as well as negative, for the health of people and the natural environment.

Alignment agreement:

The uses of technologies and any limitations on their use are driven by individual or societal needs, desires, and values; by the findings of scientific research; and by differences in such factors as climate, natural resources, and economic conditions.

Alignment agreement:

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  • New products and systems can be developed to solve problems or to help do things that could not be done without the help of technology. (Grades 6 - 8 ) More Details

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  • Requirements are the parameters placed on the development of a product or system. (Grades 6 - 8 ) More Details

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  • Requirements for design are made up of criteria and constraints. (Grades 6 - 8 ) More Details

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  • Design involves a set of steps, which can be performed in different sequences and repeated as needed. (Grades 6 - 8 ) More Details

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  • Brainstorming is a group problem-solving design process in which each person in the group presents his or her ideas in an open forum. (Grades 6 - 8 ) More Details

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  • Modeling, testing, evaluating, and modifying are used to transform ideas into practical solutions. (Grades 6 - 8 ) More Details

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  • Apply a design process to solve problems in and beyond the laboratory-classroom. (Grades 6 - 8 ) More Details

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  • Specify criteria and constraints for the design. (Grades 6 - 8 ) More Details

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  • Make two-dimensional and three-dimensional representations of the designed solution. (Grades 6 - 8 ) More Details

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  • Test and evaluate the design in relation to pre-established requirements, such as criteria and constraints, and refine as needed. (Grades 6 - 8 ) More Details

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  • Advances and innovations in medical technologies are used to improve healthcare. (Grades 6 - 8 ) More Details

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  • Biotechnology applies the principles of biology to create commercial products or processes. (Grades 6 - 8 ) More Details

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  • The use of symbols, measurements, and drawings promotes a clear communication by providing a common language to express ideas. (Grades 6 - 8 ) More Details

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  • Chemical technologies are used to modify or alter chemical substances. (Grades 6 - 8 ) More Details

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  • Identify and explain the steps of the engineering design process, i.e., identify the need or problem, research the problem, develop possible solutions, select the best possible solution(s), construct a prototype, test and evaluate, communicate the solution(s), and redesign. (Grades 6 - 8 ) More Details

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  • Demonstrate methods of representing solutions to a design problem, e.g., sketches, orthographic projections, multiview drawings. (Grades 6 - 8 ) More Details

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  • Describe and explain the purpose of a given prototype. (Grades 6 - 8 ) More Details

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  • Identify appropriate materials, tools, and machines needed to construct a prototype of a given engineering design. (Grades 6 - 8 ) More Details

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  • Explain how such design features as size, shape, weight, function, and cost limitations would affect the construction of a given prototype. (Grades 6 - 8 ) More Details

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Suggest an alignment not listed above

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
  • Introduction to Biomedical Engineering (attached handout)
  • Student Activity Worksheet (attached)

Worksheets and Attachments

Visit [www.teachengineering.org/activities/view/bones_sue] to print or download.

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There are many engineering disciplines. Do you know what I mean by "disciplines"? I mean "types" of engineers - the area or specialty that they focus on and become experts in. Can you think of some? (Listen to student ideas; examples: electrical, mechanical, chemical, biological, environmental, aerospace, civil, computer science, industrial, materials, agricultural, rehabilitation, tissue or cellular, genetic, and many more.)

Well, one of these disciplines is biomedical engineering or bioengineering. Biomedical engineers use their understanding of science and math to solve human health problems. Within the field of biomedical engineering are many specialties.

(Pass out to students the attached Introduction to Biomedical Engineering handout, which provides background information on the types of problems biomedical engineers help solve. Then review the material properties information provided in the same handout. Then review the steps of the engineering design process, also covered in the same handout, as practiced by engineers around the world.)


  1. After the Introduction/Motivation, divide the class into teams of four students each.
  2. Hand out the Student Activity Worksheets, which contains the problem (in the form of a letter to the student engineers), a cast design worksheet (five questions about the problem, materials, brainstorming ideas, best solution and sketch) and poster session requirements.
  3. The Challenge: Have students read the problem as presented in the letter to the engineers at Casts R Us. Require each team to construct a prototype with a mass of less than 300 grams. Emphasize that in addition to solving the problem, the design must be stable enough to hold the "broken bone" in place. Show students the provided materials and remind them that the materials in the box may represent any materials they would like, even ones that have not been developed yet, and they should be prepared to describe the properties of the materials they choose for their casts. In addition, each group may bring in one additional material from home.
  4. Brainstorming: Give teams 20-25 minutes to brainstorm what the problem with the cast could be and how it can be solved. Have them answer the worksheet questions to aid in their solution development process.
  5. Construct Prototypes: Using the provided materials and sketches, have students construct their prototype casts. See Figure 1 for an example prototype cast.
    A long, cylindrical object made of cotton batting and thread, wrapped with gauze. Made by students in Worcester Public Schools, MA.
    Figure 1. Example prototype cast made by a student team.
    Copyright © 2005 Tufts University, MA
  6. Test and Evaluate 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 to measure the mass of the prototypes. Have students use the digital scale to calculate the mass of their designs. Also evaluate the designs based on their stability: Do they bend or move from side to side? Do they solve the given problem? Also, require students to design tests for their prototypes that proves that the problem has been solved.
  7. Communicate Solutions: A very important skill for engineers is the ability to communicate ideas and solutions to an audience. Communicating the solution is Step #7 of the engineering design process. The audience may vary; communication may be with co-workers, superiors or customers. In this section of the activity, challenge students to communicate their solutions through poster presentations. This gives the teams the opportunity to clearly articulate their design concepts. Remind students that good presentation skills are very necessary for a wide variety of professions (including teaching!).
  8. Poster Presentation Development: Have students refer to the "poster session" page of the student worksheet so they understand the content that must be covered in their presentations. Besides containing the required information, posters must clearly explain the designs and be neat. Expect students to be prepared to speak for 3–5 minutes on their design process and results. Encourage classmates to ask questions and provide feedback.
  9. Redesign: As time permits, give teams the opportunity to redesign their casts based on feedback and suggestions for improvement from the class.


bioengineering: A discipline of engineering that applies math and science to health problems.

biomaterial: A material that can be safely implanted in the human body.

genetic engineering: A bioengineering discipline in which an organism's DNA is altered so that different proteins will be produced.

material property: A factor that describes a material and how it will behave under certain conditions.

prototype: A model or actual working version of a design concept.

rehabilitation engineer: An engineer who improves the quality of life of people with disabilities.

tissue engineer: (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.


Evaluate student prototype casts on the following criteria:

  • Responsiveness of prototype to problem presented in student letter
  • Prototype stays under 300 g
  • Student-designed testing persuasively demonstrates that prototype is stable
  • Clarity of prototype sketch (neatly drawn and includes labels)
  • Presentation clarity, content and style
  • Poster detail and neatness

Investigating Questions

  • What is biomedical engineering or bioengineering?
  • What are material properties?

Activity Extensions

Have students create digital slide presentations using Microsoft PowerPoint or other software application.


Exploring the Material World Three Classroom Teaching Modules. http://www.lbl.gov/MicroWorlds/module_index.html

It's a Materials World Student magazine from Virginia Tech. with information on different types of materials http://www.mse.vt.edu/academics/news/MW_v1n1.pdf

Bioinspired Materials and Systems, Materials Science & Engineering, Cornel University People are always looking for new materials to make life easier, safer, and more efficient. This site has some examples. http://www.mse.cornell.edu/research/bioinspired_materials.cfm

Learn more about the engineering design process at https://www.teachengineering.org/engrdesignprocess.php


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


© 2013 by Regents of the University of Colorado; original © 2005 Worcester Polytechnic Institute

Supporting Program

Center for Engineering Educational Outreach, Tufts University

Last modified: June 16, 2019


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