Hands-on Activity: Design Step 5: Construct a Prototype
Educational Standards :
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Prototyping materials and tools for the entire class to share may vary, depending on the project. Some suggested items include:
Introduction/Motivation (Return to Contents)
How does a typical engineering design loop begin? (Take suggestions from the students.) That's right. The engineering design process begins by defining the engineering challenge, performing background research, brainstorming potential solutions, and evaluating several alternatives. And what is next? (Listen to suggestions from the students.) Next, an engineering team synthesizes this information to begin the product manufacturing process. Many times, something that works on paper proves to be very difficult to build. To help engineering teams assess the "buildability" of their project concept, they often create prototypes.
A prototype is a working model of a product that is used for testing before it is manufactured. Prototypes help designers learn about the manufacturing process of a product, how people will use the product, and how the product could fail or break. A prototype is not the same thing as a model. A model is used to demonstrate or explain how a product will look or function. A prototype is used to test different working aspects of a product before the design is finalized.
For example, a team of engineers designing a new cell phone might produce several cardboard and paper models to illustrate how the final product would look and feel. They may survey the general public to gain feedback about how the cell phone could look. The team might build a sturdier plastic prototype to test how easily the cell phone could break when dropped. If the prototype does not meet the team's design requirements, then they may complete an "iteration." Iteration is when engineers try again and re-design, re-build and re-test. Engineers often iterate many times before determining the final solution to a problem. Once a successful prototype has been developed, the engineering team can use it as a mock-up for full-scale manufacturing.
Your team will follow a similar process. By building a prototype, you should be able to determine if your chosen design solution is feasible and which aspects of your design needs special materials or further refinement. You will also ask other people to test your prototype to help you identify any problems a user might encounter. You may even have time to complete a few iterations, or modifications, to your prototype.
(Note: After conclusion of this activity, proceed to the next activity in the series, Design Step 6: Evaluate/Manufacture a Final Product.)
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
New designs often have unexpected problems, and it is often difficult to determine whether a new design or product will perform as intended. Prior to large-scale manufacturing of a product, engineers often build prototypes. A prototype is a model of a product used to explore design alternatives, test theories, confirm performance and ensure the product is safe and user-friendly. Engineers use prototypes to figure out specific unknowns still present in the design.
For example, a student team designing a prosthetic hand that rolls dice could build a prototype using simple materials such as wood, rubber bands and string to test that the prosthetic hand performs the desired function of rolling and picking up dice. In most cases, an iterative series of prototypes is designed, constructed and tested as the final design emerges, is refined and becomes ready for production.
A philosophy often repeated and credited to Tom Kelley of IDEO, a successful worldwide engineering design and innovation consulting firm, is, "Fail often to succeed sooner." It might be helpful for students in the midst of prototyping iterations to see the value of this approach as expressed by professional designers. We learn more from failures than successes.
Often, the term prototype is interchanged with the term "model," which can cause confusion. While several types of prototypes exist, for the purpose of this activity, we will make the following distinction: Whereas a model is used to demonstrate or explain how a product will look or function, a prototype is used to work out the kinks in a design or to try new ideas. Keep in mind that prototypes are unrefined versions of a future product. Most companies do not show prototypes to the general public to ensure that the public's opinion is based on the final product.
In some cases, engineers "rapid prototype" a part. Rapid prototyping is the automatic construction of physical objects using additive manufacturing technology and computer-aided design (CAD) software.
Basically, a virtual design from CAD software is "read" by a rapid prototyping machine that divides the design into thin horizontal slices. The machine then lays down successive horizontal layers of liquid or powder (such as ABS plastic material) and adhesive in the shape of the virtual design. The primary advantage of rapid prototyping is the ability to create almost any shape or feature, including assemblies with moving parts.
Before the Activity (Teacher Prep)
With the Students
1. Explain to students the purpose of building prototypes. Mention that several types of prototypes exist, but we will focus on creating prototypes for the purpose of testing different working aspects of a product before the design is finalized.
2. (optional) Ask students the Investigating Questions about creating and testing prototypes.
3. Show students the available building materials (or allow them to bring in their own if this was established in advance).
4. Review the Foam Core Tips Handout (if applies), or any other information on material use or tool safety.
5. Lead the pre-activity assessment (as described in the Assessment section) to give students a chance to sketch their ideas before constructing prototypes. Students are asked to complete a more detailed sketch of their design than in previous activities. Have them label materials and specify dimensions.
6. Give students "free time" to experiment with the materials and begin construction. Answer questions as they arise.
7. Early in the construction process, briefly stop the class to lead a mini design review as described in the Assessment section (activity embedded assessment). Have each team show the class their initial prototype, explain its purpose, and describe any challenges they have encountered during the build process. Follow with a class discussion to collaborate in figuring out possible solutions.
8. Once teams have finished the build process, have them swap prototypes and engage in the user testing as described in the Assessment section (post-activity assessment).
9. Give teams enough time to create at least one iteration of their prototypes. Have students add modifications to their sketches (made in Step 4), modify or re-build their prototypes, and proceed through another round of user testing for each iteration.
Safety Issues (Return to Contents)
Troubleshooting Tips (Return to Contents)
If students become frustrated with the way their initial prototypes look, remind them that prototypes are used to test out new ideas and are not meant to look perfect!
Investigating Questions (Return to Contents)
Use the following discussion questions to help students gain understanding of an important aspect of engineering problem solving: creating and testing prototypes.
Assessment (Return to Contents)
Sketch It! Have students use their initial sketches or outlines created in the Design Step 3 activity to generate more detailed sketches of their envisioned prototypes, labeling them with dimensions and materials. Now that they have seen the available materials, they should have a sense for the degree of the complexity achievable in this first prototype. Review the sketches with the students to check that they are designing prototypes, not models. If time allows, have them draw the prototype sketches to scale.
Design Review: Briefly stop the prototype construction process to bring the class together as a group. Ask each team to show its initial prototype, explain its purpose (what the team is attempting to test) and describe any challenges encountered during the build process. Write these challenges on the board and lead a class brainstorming session so students may offer solutions to other teams' challenges. (Note: Alternative options for performing design reviews include: asking the team to present to a small "client focus group" that includes the teacher and a few others, having students rotate around the room and review for one other team, or asking another class to come in to listen and provide feedback to initial design descriptions.)
User Testing: To simulate user testing, have each team swap prototypes with another team. Ask teams to give each other feedback:
Reflection: After user testing, ask the design teams to reflect on the feedback received. Have them write short documents for the teacher summarizing the feedback and what changes they intend to make in the next iteration of their designs.
Activity Extensions (Return to Contents)
Limitations to Prototypes: Have student teams brainstorm the limitations of prototypes and generate lists of ideas. Engage the class in a discussion of these limitations and expand the discussion to talk about what can be done to accurately determine these factors for final production. For example, limitations might include evaluating costs, time to build, material function and actual environmental impact.
References (Return to Contents)
Prototype. Last updated January 1, 2010. Wikipedia, The Free Encyclopedia. Accessed January 27, 2010. http://en.wikipedia.org/wiki/Prototype
Rapid prototyping. Last updated January 13, 2010. Wikipedia, The Free Encyclopedia. Accessed January 27, 2010. http://en.wikipedia.org/wiki/rapid_prototyping
Sloane, Paul. Failure is the Mother of Invention. Published October 13, 2004. Innovation Tools. Accessed February 9, 2009. http://www.innovationtools.com/Articles/EnterpriseDetails.asp?a=158
ContributorsLauren Cooper, Malinda Schaefer Zarske, Denise W. Carlson
Copyright© 2009 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.