Week 2
Engineering design
What is engineering?
Engineers design solutions to human problems, utilizing models(often mathematical) of how materials, systems, and people behave.
For example, children building sand castles develop an expert knowledge of the mechanical properties of sand, both wet and dry- how much will hold a shape, how to use forms to shape it, how tall a tower or wall of a given size can be built, how to reinforce it with sticks and pebbles.
They build in a judgment-free environment, and are able to go through many iterations, pushing paste failure, until they reach the desired result.
A similar design environment should be created in the classroom.
Engineers have to understand human needs
In designing solutions to human problems, engineers first need to understand the problem they are trying to solve. This is done through empathy with the user, observing the user in their life, and interviewing them to better understand the problem.
Engineers solve problems by creating new products, systems, or environments. Before creating something, it is very important to define the problem.
Otherwise, you might build something only to find that it does not meet the original goal!
To define your problem, answer each of these questions:
What is the problem or need?Who has the problem or need?Why is it important to solve?
The answers to these three questions are the what, who, and why of your problem. Your problem statement should incorporate the answers as follows:
[Who] need(s) [what] because [why].
In design terms, who, what, and why can be defined as:
Who = user
What = need
Why = insight
The problem statement for any good engineering design project should be able to follow the format shown. Your problem statement should always look like this:
need(s) because
.
If you are improving an existing solution for your project, keep in mind that the improvements will be part of your problem statement. Making something better, faster, or cheaper should be part of your statement—either in the "what" portion and/or the "why" portion. For example, if you are improving a car radio, your problem statement might be:
People need cheaper and better-performing car radios, because current radios are expensive and poor at picking up weak radio signals.
In-class activity: Interview your partner about their needs as a student or as a teacher
Engineers need expert knowledge to be able to model how materials and systems will behave
Engineers need to understand the properties and characteristics of the materials and system they are using to create their design, whether the strength of a beam, the traffic capacity of a road or bridge, or the rules governing the computer program they are using.
Before we ask students to design things, they need to have experience working with the materials they are working with, and common design solutions.
Engineers design things based on their expert knowledge of the properties of the materials they are working with, or established design solutions or practices.
For example, children building sand castles develop an expert knowledge of the mechanical properties of sand, both wet and dry- how much will hold a shape, how to use forms to shape it, how tall a tower or wall of a given size can be built, how to reinforce it with sticks and pebbles.
Engineering problems have many possible solutions
Engineering design is an iterative cycle of prototype, testing, critique, and improvement
Engineers need technical skills to put ideas into practice
Engineering design involves trade-offs
You can't get something for nothing. Adding features requires money, time, and expertise.
Example 1:
Pizza Engineering: How many pizzas do you order if 10 friends are coming for a pizza party?
Engineering Model: Average person eats 2 slices, but some might eat more.
Calculation: If 8 slices per pizza, you might order 3 pizzas( safety factor of 2 slices) or 4 pizzas ( safety factor of 10 slices). The most efficient design is the least expensive one that meets the performance criteria. Engineering designs almost always involve trade-offs- speed vs force, cost vs performance.
Example 2:
How tall a tower can you build with a cubic foot of beach sand? With a pound of plasticine?
Answer: It depends on the water content of the sand or the temperature of the plasticine.
Example 3: How much power can be generated with a 2-foot diameter wind turbine?
The equation for wind power(P) is given by P= 0.5 x ρ x A x Cp x V3 x Ng x Nb
where, ρ = Air density in kg/m3, A = Rotor swept area (m2). Cp = Coefficient of performance V = wind velocity (m/s) Ng = generator efficiency Nb = gear box bearing efficiency.
Example 4: Traffic Capacity- How many cars per hour can a road safely handle?
Using the relation, C = 1000*V/S, one can easily determine the Theoretical Maximum Capacity.
Here, C = Capacity of a single lane, vehicle per hour.
V = Speed, kmph.
S = Average centre to centre spacing of vehicles, when they follow one behind the other as a queue or space headway, where S= 0.2V(km/hour)+6
The capacity depends upon the Speed and Spacing. Spacing is governed by the safe stopping distance required by the rear vehicle in case the vehicle ahead stops suddenly.
ELEMENTS OF SUCCESSFUL DESIGN CHALLENGES IN MIDDLE SCHOOL:
Clear goals: Challenges should reveal to students the exact nature of what is being asked of them. Challenges should invite students to chose (or to consider) strategies they feel appropriate to attain the goal.
Tests against nature: Designs should be evaluated using highly reliable tests against nature and not rely on complex rubrics or subjective judgments of teachers or students.
Prototype design: Students vary in their construction skills and level of confidence. Building an initial “cookbook” design, albeit a poor performer, is a necessary first step to engage students, develop rudimentary construction skills, and familiarize students with test procedures.
Multiple iterations: Students learn from their failures as well as successes. To encourage the testing of ideas, devices should be quick to build and modify so that many tests can be performed in a short period.
Large dynamic range: Whenever possible, device performance should increase dramatically over several days of building. A high signal-to-noise ratio is necessary for students to find experiments and their data convincing and to uncover the underlying science.
Employ purposeful record keeping: Student records should be formative, capturing all attempts and trials. They need to function as a resource for the resolution of claims of first ideas and for the focus of class discussions.
Engineering Competitions in the Middle School Classroom: Key Elements in Developing Effective Design Challenges
Philip M. Sadler,Harold P. Coyle &Marc Schwartz
Pages 299-327
Drawing in STEM
Drawing is the essential STEAM skill, that lies at the intersection of science, engineering, technology, art, and mathematics. Even more than photography, drawing, whether with traditional or computer-based tools, forces you to LOOK and ask questions. What are the dimensions of each part? What materials is it made of? How are they connected? How do they move?
Introduction to Scientific Sketching
https://www.calacademy.org/educators/lesson-plans/introduction-to-scientific-sketching
K-12 Engineering Resources:
Design Squad Global https://pbskids.org/designsquad/parentseducators/
Exploratorium-The Tinkering Studio https://www.exploratorium.edu/tinkering/projects
MakerEd-Projects https://makered.org/resources/projects-learning/
“Projects & Learning Approaches” includes a wide variety of information, meant to provide educators and facilitators with ideas for short-term activities as well as open-ended long-term projects, curriculum samples, examples of facilitation methods and practices, and the pedagogies and values aligned with making.
Microsoft-Hacking STEM https://www.microsoft.com/en-us/education/education-workshop
Try Engineering https://tryengineering.org/teachers/lesson-plans/
The Bridge Designer http://bridgedesigner.org/
The Bridge Designer is a free educational software package designed to provide middle-school and high-school students with a realistic introduction to engineering through the design of a highway truss bridge