Grade by Grade
A. Design Processes and Related Skills · Design Skills: From Idea to Tested Prototype

The Engineering Design Process and STEM

A1.2About 70 minutes
Learning goals
  • I can describe each step of the engineering design process and explain why it is a cycle, not a straight line.
  • I can tell an open-ended design problem from a closed question.
  • I can apply science, technology, engineering and mathematics (STEM) concepts when I develop a project.
  • I can use a technological concept, a design consideration and a STEM concept together to make a design decision.

Words to know

engineering design process
A step-by-step but repeating method for solving design problems: define, research, generate ideas, choose and plan, build, test, refine and communicate.
prototype
An early working model used to test a design idea before the final product is made.
iteration
One pass through build, test and refine; designs improve through several iterations.
STEM
Science, technology, engineering and mathematics.
design brief
A short statement that describes the problem, the user, the criteria and the constraints.
design consideration
Anything the designer must keep in mind, such as the user's needs, safety, cost, accessibility or the environment.
open-ended problem
A problem with many possible good solutions, not one right answer.

The cardboard chair challenge

Imagine your teacher hands you a pile of cardboard, a roll of tape and this challenge: build a stool that holds a Grade 9 student for 30 seconds. What do you do first?

Most people start cutting right away. Most of those first stools collapse. Teams that stop, think, sketch, test a small model and then build almost always do better. That is the engineering design process in action.

Remember from Grade 8

In Grade 8 you used an 8-step design process to build a lifting system: define, research and brainstorm, plan, build, test, evaluate, improve, communicate. In this course you will use the same thinking with more independence, for products and services in many technology areas, and you will document every step like a professional.

The steps

  1. Define the problem. Who is it for? What need does it meet? Write a design brief with criteria (what success looks like) and constraints (limits like time, cost and materials).
  2. Research. Find out what already exists, what the user needs, which materials and methods could work and what safety rules apply.
  3. Generate ideas. Brainstorm and sketch several different solutions. Quantity first; judge later.
  4. Choose and plan. Compare ideas against your criteria, pick the best one, draw it with measurements and plan the materials, tools, steps and time.
  5. Build a prototype. Make a working model, often from cheap materials first.
  6. Test and evaluate. Does it meet each criterion? Collect data.
  7. Refine. Change the design to fix problems, then test again.
  8. Communicate. Share the final design, your data and your reasons with the client or audience.

Different companies and textbooks use slightly different names and numbers of steps (some use 5 or 6). The key ideas are always the same.

1 Define2 Research3 Generate ideas4 Choose and plan5 Build prototype6 Test and evaluate7 Refine8 Communicateiterate:build, test, refine, repeat
The engineering design process. Steps 5, 6 and 7 form a loop: you build, test and refine as many times as you need (dashed arrow from Refine back to Build) before you communicate the final design.

Why a cycle?

Real designers almost never get it right the first time. Testing shows problems, and fixing them often means going back to an earlier step. You might discover during testing that the user also needs the stand to fold flat. That sends you back to define. This is normal. Professionals call it iteration, and each loop makes the design better.

STEM in every project

The curriculum asks you to apply science, technology, engineering and mathematics concepts as you develop projects.

  • Science: forces, centre of gravity, friction, heat transfer, properties of materials, electricity.
  • Technology: tools, materials, processes and the technological concepts from the last lesson.
  • Engineering: the design process itself, plus testing and improving.
  • Mathematics: measurement, unit conversion, area and volume, angles, ratios and scale, budgets, the Pythagorean theorem and graphs of test data.

A good design decision usually combines a technological concept, a design consideration and a STEM concept, like the example below.

Worked example

Using STEM to size a tablet stand

Amira is designing a tablet stand for her grandfather. The stand's base will be 24 cm long, and a vertical brace at the front of the base is 18 cm tall. The back support runs from the back corner of the base to the top of the brace. How long must she cut the back support?

  1. The base and the brace meet at a right angle, so the three parts form a right triangle. The back support is the hypotenuse.
  2. Use the Pythagorean theorem: a² + b² = c², so 24² + 18² = c².
  3. 576 + 324 = 900, so c = √900 = 30 cm.
  4. Add a little for joining: if she folds a 2 cm tab at each end to glue, she cuts 30 + 2 + 2 = 34 cm.
  5. STEM check: science (centre of gravity): the tablet's weight should fall inside the base so the stand does not tip. Technology (structure): the triangle shape is rigid. Math: the Pythagorean theorem gave the length.

Cut the back support 34 cm long (30 cm plus two 2 cm glue tabs).

base: 24 cmbrace: 18 cmback: ? cma² + b² = c²24² + 18² = c²576 + 324 = 900c = √900 = 30 cm
Side view of the tablet stand, drawn to scale. The back support is the hypotenuse of a right triangle, so the Pythagorean theorem from Grade 8 math gives its length: 30 cm.
Worked example

Applying the design process to a service

Ethan's class will run a hot chocolate booth at the school Winter Carnival. Show how the first four steps of the design process apply to a service.

  1. Define: Serve hot chocolate to about 150 people in 90 minutes, safely, for $1 a cup, with no line longer than 5 minutes.
  2. Research: How much powder and water per cup? (Read the package.) How hot is too hot to serve? How do food booths keep hands and cups clean? How many cups can one urn hold?
  3. Generate ideas: one serving line with one urn; two lines with two urns; pre-filled cups on a tray; a self-serve station with a staff member watching.
  4. Choose and plan: compare against the criteria. 150 people in 90 minutes is 150 ÷ 90 ≈ 1.7 people per minute, so the booth must serve one person about every 36 seconds (5400 s ÷ 150). Two lines with two urns gives the most time per cup, so the class chooses that and plans roles, a layout sketch and a timeline.

The design process works for services too: the "prototype" might be a practice run with 10 classmates before the carnival.

Hands-on activity

Mini design cycle: the paper tower

You need: 10 sheets of scrap paper, 30 cm of masking tape, a ruler or tape measure, a timer, and a small object such as an apple or a juice box for the load.

Brief: build the tallest free-standing paper tower that holds the load on top for 10 seconds, in 20 minutes.

  1. Define (2 min): write the criteria and constraints in your notebook.
  2. Generate ideas (3 min): sketch two different tower ideas (for example rolled tubes vs. a folded triangular column).
  3. Choose one and build a first prototype (6 min).
  4. Test: measure the height in cm and check whether it holds the load for 10 s. Record the results.
  5. Refine (6 min): change one thing and test again. Record the new height.
  6. Communicate: write three sentences about what you changed and why it helped (or did not).

STEM link: which shapes resisted bending best? Why did a wider base help? (Hint: centre of gravity.)

What to look for: two sketches, recorded measurements for at least two tests, and a reason for the change.

Just for fun

A design engineer's favourite tool is not a hammer or a laptop. It is the eraser. Every great design has been rubbed out and redrawn many times. That is iteration with crumbs.

Your turn

1

Put these steps in order: test and evaluate, define the problem, build a prototype, generate ideas, communicate, research, refine, choose and plan.

2

What is a prototype and why build one?

3

Is "What is 3 × 4?" an open-ended problem? Explain.

4

Give one science concept that could help you design a stable bookshelf.

5

A ramp rises 30 cm over a horizontal run of 40 cm. How long is the sloped surface?

6

Why do designers say the process is a cycle?

7

Name the step: Ethan's class runs a practice booth with 10 classmates and times each sale.

More practice: warm-up

1

What does STEM stand for?

2

What is the first step of the design process?

3

What is a design brief?

4

What word means repeating build, test and refine?

5

Which step shares the final design with others?

More practice: on your own

1

A shelf bracket is a right triangle with legs 15 cm and 20 cm. How long is the diagonal brace?

2

A team skips research and builds a birdhouse with a hole too small for the birds they wanted. Which step would have prevented this, and how?

3

Why is it useful to brainstorm several ideas before choosing?

4

A booth must serve 120 people in 60 minutes. How many seconds per person is that?

5

Give one technology concept and one math concept used when designing a bike rack for a school.

Challenge

1

A wheelchair ramp in many building guidelines is often limited to a slope of 1:12 (1 unit of rise for every 12 units of horizontal run). A doorway is 36 cm above the ground. What horizontal run is needed, and about how long is the sloped surface? Round to the nearest centimetre.

2

Describe how you would go "back" in the design process if testing showed your tablet stand slid across the table. Which step would you return to and what might you change?

3

Explain how the design process for a service (for example, a dog-walking business) is similar to and different from the process for a product.

Check your understanding

Quiz

1.

Which is the first step of the engineering design process?

2.

What is a prototype?

3.

Why is the design process described as a cycle?

4.

A brace forms the hypotenuse of a right triangle with legs 6 cm and 8 cm. How long is it?

5.

Which is an open-ended design problem?

6.

Planning that heavy items go low on a shelf so it does not tip applies which STEM idea?

For parents and teachers

Big idea: Expectation A1.2 asks students to apply technological concepts, design considerations and STEM (science, technology, engineering and mathematics) concepts as they develop projects. The engineering design process is the framework for the whole unit.

How to help at home:

  • During the paper tower activity, resist fixing the design for your teen. Instead ask, "What did the test show? What will you change?"
  • Point out iteration in everyday life: a recipe adjusted after the first try, a route to school changed after a slow day.

Common difficulties:

  • Skipping straight to building. Insist on at least two quick sketches first.
  • Treating failure as the end. A failed test is data. Praise good changes, not just good results.
  • Pythagorean theorem errors. Remind them to square first, add, then take the square root (not add the sides then square).

Safety: the activities use paper and tape only. If your teen wants to cut cardboard later in the unit, an adult should handle or supervise any utility knife.