B. Engineering Design
Engineering design (sometimes called technological design) is an iterative, systematic process for solving problems that involves creativity, experience, and accumulated disciplinary knowledge. As used in this framework, engineering design is a broad term, including processes such as architectural design, manufacturing design, industrial design, and software design.
Much like scientific inquiry, engineering design is a dynamic process, not a rigid method. As engineering and science are often confused, it is helpful to draw a distinction. Scientific inquiry begins with a question and proceeds to generate and test hypotheses until the question is answered. In contrast, engineering design begins with a problem and proceeds to generate and test solutions until a preferred solution or solutions are reached. Whereas science seeks to understand, engineering seeks to meet people's needs.
The engineering design process usually begins by stating a need or want as a clearly defined challenge in the form of a statement with criteria and constraints. For example, a group of engineers might be given the task of designing, for example, a cell phone with a particular set of features, of a particular size and weight, with a certain minimum battery life, and that is able to be manufactured at a particular cost.Criteriaare characteristics of a successful solution, such as the desired function or a particular level of efficiency.Constraintsare limitations on the design, such as available funds, resources, or time. Together, the criteria and constraints are referred to as therequirementsfor a successful solution.
Once the challenge is defined, the next steps are often to investigate relevant scientific and technical information and the way that similar challenges have been solved in the past and then to generate various possible solutions. This generation of potential solutions is the most creative part of the design process and is often aided by sketching and discussion. Using a process of informed decision-making, the designer or design team compares different solutions to the requirements of the problem and either chooses the most promising solution or synthesizes several ideas into an even more promising potential solution. The next step is usually to try out the solution by constructing a model, prototype (first of its kind), or simulation and then testing it to see how well it meets the criteria and falls within the constraints. An additional characteristic of engineering design is that ideas are tested before investing too much time, money, or effort.
A person does not have to be an engineer to employ an engineering design process. Children can use this process to create a new toy, teachers can use it to plan a semester of lessons, and anyone can use it to address a need or desire encountered in everyday life.
The result of an engineering design process is not always a product. In some cases the result may be a process (such as a chemical process for producing an improved paint) or a system (such as an airline control system or a railway schedule), or a computer program (such as a video game or software to forecast the weather or model financial markets).
When designing, it is important to take into account the entire life cycle of the product or process, including maintenance, troubleshooting, potential failure modes, impacts on the environment, and effects on society. Designing usually concludes with a presentation to clients or other interested parties (often classmates) on the preferred solution.
Optimization, which is sometimes part of designing, means finding the best possible solution when some criterion or constraint is identified as the most important and others are given less weight. For example, optimizing the design of a pen might mean designing for lowest cost, best ink flow, or best grip, but not all three. Optimizing the design of an airplane engine usually means maximizing safety. In some engineering disciplines the entire engineering process is referred to as "optimization under constraint."
It bears emphasizing that engineering design is not a rigid method. Different instructional materials define it differently, although most definitions specify a sequence of steps, ranging from 5 steps for elementary students to 8 or 10 steps for high school students. The steps need not be followed in order. An experienced engineer might skip ahead a step or two or go back one or two steps. Or after generating solutions it may become clear that the problem was poorly defined, and so it is best to restart the process from the beginning. Regardless of these differences in definition and use, engineering design always begins with a problem and ends with one or more solutions.
Key principles in the area of Engineering Designthat all students can be expected to understand at increasing levels of sophistication are:
- Engineering design is a systematic, creative, and iterative process for addressing challenges.
- Designing includes identifying and stating the problem, need, or desire; generating ideas; evaluating ideas; selecting a solution; making and testing models or prototypes; redesigning; and communicating results.
- Requirements for a design challenge include the criteria for success, or goals to be achieved, and the constraints or limits that cannot be violated in a solution. Types of criteria and constraints include materials, cost, safety, reliability, performance, maintenance, ease of use, aesthetic considerations, and policies.
- There are several possible ways of addressing a design challenge.
- Evaluation means determining how well a solution meets requirements.
- Optimization involves finding the best possible solution when some criterion or constraint is identified as the most important and other constraints are minimized.
- Engineering design usually requires one to develop and manipulate representations and models (for example, prototypes, drawings, charts, and graphs).
Fourth-graders should know that engineering design is a purposeful method of solving problems and achieving results. They should be able to state a simple design challenge in their own words, test a solution, and communicate the findings with drawings and models.
Eighth-graders should be able to carry out a full engineering design process to solve a problem of moderate difficulty. They should be able to define the challenge in terms of criteria and constraints, research the problem, generate alternative solutions, build and test a model or prototype, redesign, and communicate the findings.
Twelfth-graders should be able to meet a complex challenge, weigh alternative solutions, and use the concept of trade-offs to balance competing values. They should be able to redesign so as to arrive at an optimal solution.
B. Engineering Design Goals
Fourth-graders should start to answer the question "How are technologies created?" by confronting simple yet systematic design challenges. Eighth-graders should be able to use a more elaborate engineering design process, including problem definition, the use of prototypes, testing and iteration, and trade-offs. Twelfth-graders should have a deep understanding and a broad array of design skills, including optimization.
Table 2.7 Engineering Design assessment targets for grades 4, 8, and 12
|Grade 4||Grade 8||Grade 12|
Students know that:
D.4.6:Engineering design is a systematic and creative process for meeting challenges. Often there are several solutions to a design challenge. Each one might be better in some way than the others. For example, one solution might be safer, while another might cost less.
Students know that:
D.8.6:Engineering design is a systematic, creative, and iterative process for meeting human needs and wants. It includes stating the challenge, generating ideas, choosing the best solution, making and testing models and prototypes, and redesigning. Often there are several possible solutions.
Students know that:
D.12.6:Engineering design is a complicated process in which creative steps are embedded in content knowledge and research on the challenge. Decisions on trade-offs involve systematic comparisons of all costs and benefits, and final steps may involve redesigning for optimization.
D.4.7:Requirements for a design include the desired features of a product or system as well as the limits placed on the design, such as which materials are available.
D.8.7:Requirements for a design are made up of the criteria for success and the constraints, or limits, which may include time, money, and materials. Designing often involves making trade-offs between competing requirements and desired design features.
D.12.7:Specifications involve criteria, which may be weighted in various ways, and constraints, which can include natural laws and available technologies. Evaluation is a process for determining how well a solution meets the requirements.
Students are able to:
D.4.8:Use a systematic process to design a solution to a simple problem.
Students are able to:
D.8.8:Carry out a design process to solve a moderately difficult problem by identifying criteria and constraints, determining how they will affect the solution, researching and generating ideas, and using trade-offs to choose between alternative solutions.
Students are able to:
D.12.8:Meet a sophisticated design challenge by identifying criteria and constraints, predicting how these will affect the solution, researching and generating ideas, and using trade-offs to balance competing values in selecting the best solution.
D.4.9:Construct and test a simple model to determine if it meets the requirements of a problem.
D.8.9:Construct and test a model and gather data to see if it meets the requirements of a problem.
D.12.9:Construct and test several models to see if they meet the requirements of a problem. Combine features to achieve the best solution.
D.4.10:Communicate design ideas using drawings and models.
D.8.10:Communicate the results of a design process and articulate the reasoning behind design decisions by using verbal and visual means. Identify the benefits of a design as well as the possible unintended consequences.
D.12.10:Communicate the entire design process from problem definition to evaluation of the final design, taking into account relevant criteria and constraints, including aesthetic and ethical considerations as well as purely logical decisions.