B. Engineering Design

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. Criteria are characteristics of a successful solution, such as the desired function or a particular level of efficiency. Constraints are limitations on the design, such as available funds, resources, or time. Together, the criteria and constraints are referred to as the requirements for 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 Design that 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