Descriptions and graphics concerning the Engineering Design Process (EDP) can be found in many different resources and websites. They generally contain 6-8 steps in a cyclic, iterative arrangement. This can sometimes be overwhelming to a teacher who is new to Engineering Design projects and activities, particularly when one considers the dynamic environment of a classroom and the need to manage multiple groups of students. At ProjectEngin, we believe that everyone “engineers” at times and we work to help teachers fit that natural inclination into the EDP. In our workshops, we often find that dividing the Engineering Design Process (EDP) into three phases helps newcomers (both teachers and students) navigate through it more intuitively. The two previous parts of this series focused on Phase 1, Know Your Problem, and Phase 2, Knowing Your Options. The final phase, Develop a Solution, ties it all together and often sets the stage for revisiting earlier steps.
Our use of three phases is not arbitrary. It has been developed based on observations and input from the teachers we work with and from an understanding of the process of designing.
Don Norman The Design of Everyday Things
The three phases reflect the need to move back and forth between convergent and divergent thinking throughout the design process.Keeping in mind the different types of thinking involved in the different steps and phases of the EDP helps teachers to keep the focus on skills and the value of the overall process.
This last part of our 1, 2, 3 Engineer series focuses on Phase 3 – Develop a Solution. It begins with a transition from the divergent thinking processes evident in Phase 2 to a group agreement on the best option for moving forward. Once multiple ideas have been put forth and explored, the group needs to decide which best fits their criteria and the given constraints. This decision- making process can be challenging. There many options for managing it and some will be discussed in more detail in a future blog post. We highly recommend that, at a minimum, the group settle on 3-5 options and then quietly vote by individual ballot using a ranking scheme. Ballots can then be tabulated and the options can be listed from most to least popular. Skipping the actual voting process and allowing a simple verbal group consensus sometimes creates a “groupthink” mentality or a situation where one member of the group dominates. Keep it democratic by allowing each person to have a say via a ballot.
The key steps in Phase 3 are present in the box in the graphic above: (1) Prototype, (2) Test, and (3) Modify in order to optimize. Let’s look at each in a little more detail.
Prototype: Prototypes can take many forms and can have varied functions. From the start, stress to your students that a prototype is, first and foremost, an aid to visualizing a solution. In some cases, a prototype can be a simple sketch that helps you explain an idea. It can also be as advanced as a full-size functioning model of a new product. In most classroom projects, a prototype will be a small scale model of a device or solution. It will often be made of materials chosen to substitute for the actual materials that would be used in the final full-size version.
Prototypes of prosthetic hands; to be tested for grip
The reasons that you have students prototype is for them to have something that can help them explain their approach, test for some functionality, or enable end-users to provide feedback. It is critical to remember that this is the role of the prototype. It is not mean to be perfect and it should never be more than 20-30% of the overall grade for any project. The real learning happens in following the full process above, not in simply making a prototype. We never advocate that you make the final prototype the summative assessment for the project.
Testing: Teachers and students always have lots of questions about what it means to test a prototype. Think of testing as needing to evaluate one or more of the following:
Evaluating functionality or cause and effect. Does a given input create the desired output? This type of testing is closest to the testing typically done in a science experiment. Characteristics can include dependent and independent variables, a control, consistent and precise measurement.
Determine the reliability or repeatability of a device or product. This type of testing is similar to testing routinely done for consumer safety and use. Does it perform safely and/or can it repeat the same function numerous times? Bicycle helmets may be dropped over and over again and at forces in excess of those expected in a crash, pen tops are clicked thousands of times, chairs are subjected to loads above the assumed weight of a large person. This video of how cell phones are tested can be helpful in understanding this type of testing.
Obtaining customer and end-user feedback. Do people like it, do they use it correctly, would they buy it, what might make it more attractive to them? This type of test marketing is routine for most consumer goods. The most effective way to obtain good data in this case is through a combination of Likert scale (1-5) survey questions and observations and interviews.
Work with your students to identify what feature needs to be tested, what procedure should be followed, what data should be obtained, how it will be analyzed, and what the standard for acceptable performance should be.
Modification: This is where Engineering testing differs from science experiments. Engineers use testing data to modify and improve their designs; scientists are typically seeking verification or refutation. We have noted that many teachers skip the modification phase at first. This is most likely due to time constraints since most “first runs” of projects take about 20% longer than planned. We urge you not to skip this step. If time is too short to allow for physical modifications to a design, or if the testing was somewhat destructive in nature, asking students to answer a question or two about how they would modify their design can be part of a good summative assessment. Whether you allow time for actual modification or ask for a written description of the planned modification, keep a few things in mind:
Allow one modification at a time. That is the only way to gauge the impact of a modification. Think of it as isolating a variable in science experiments.
Limit We rarely allow more than three and students are aware of that from the start of the project. This creates more focus during the initial design stages. Too many modifications are collectively a new design and you risk losing some of the value of the overall process.
Always require justification in terms of some combination of science, math, and testing data and feedback. And always keep the focus on meeting constraints and criteria. Meeting criteria and constraints drives the need to optimize, which means to work towards the best solution possible given your goals and the resources and limitations that you have. It is a key feature of the EDP and it is highlighted in the NGSS. Optimization brings the design process full circle, by asking students to justify their solution in terms of problem definition. In order to fully document the development process, revisions and modifications in industry are often tracked by modification forms. We use one with a space for a description of the modification, the reason or rationale for it, and the expected and actual results. Students often opt to provide a before and after sketch to further document the change.
Engineers are never done and any part of the EDP can be revisited or repeated in order to develop a product or process that solves the given problem. There is never a 100% perfect answer in Engineering. It is always a matter of developing innovative ways to best meet the criteria and constraints that define a problem. To do that you need to understand the limitations and goals that you have, investigate the possibilities available for solutions, and demonstrate the ability of your proposed solution to solve the problem. In other words, you need to engineer!