Lesson 5 of 6
Engineer for People and the Planet
Students take on real-world engineering by designing a model water filter, a flood barrier, or a redesign of an everyday product, weighing what real users need against real constraints.
- Estimated time
- 50-60 minutes
- Main project
- Water Filter, Flood Barrier, or Product Redesign
The problem
Design a solution that helps people or protects the environment. First decide who you are helping and what problem you are solving for them, then build a model that does the job with the materials you have.
The rules
- Name your user and the one problem you are solving for them before you build.
- Use only the provided materials, and note any that cost money or could harm the environment.
- Safety: for water filter models, filtered water is for testing only and must never be tasted or drunk.
Where you see this in real life
A lot of engineering is not about gadgets - it is about keeping people safe, healthy, and able to do everyday things. These designs solve real problems for real communities.
- Clean water systems
- Flood protection
- Recycling
- Safer products
- Reusable packaging
Key ideas
- Engineering for people
- Engineers often solve problems for real people, not just for fun. The people who will use a design come first.
- Materials matter
- Different materials behave differently - some soak up water, some block it, some bend or break. Picking the right one is part of the design.
- Constraint
- A limit on your design, like which materials you can use, how big it can be, or how much time you have.
- Tradeoff
- When making one thing better makes another thing harder, so you have to choose what matters most.
- Design for the user
- Good designs start from what the user actually needs, and get tested by someone using them.
See how it works
Materials
- Cups
- Coffee filters
- Cotton balls
- Gravel
- Sand
- Cardboard
- Tape
- Straws
- Paper
- Index cards
- A water testing container
No problem if you are missing something
- A cut plastic bottle instead of a cup for the filter
- A baking tray or foil to hold the water for a flood barrier
- Clay or playdough to shape a barrier wall
Compare your materials
Materials behave differently. Use this to decide which material does which job.
- Cardboard
- Stronger than paper. Good for panels, decks, and bases.
- Paper
- Light and bends easily. Much stronger when folded or rolled.
- Straws
- Light and handy for frames, but bend if nothing supports them.
- String
- Great for pulling, but it cannot push - it just goes slack.
- Tape
- Useful for joining parts, but joints can fail if overloaded.
Plan before you build
Engineers plan before they build. Work through these before you pick up any tape.
- 1Draw your idea before you build it. A rough sketch is fine.
- 2Label the strongest part of your design, and the part you are least sure about.
- 3Predict what might fail first when you test it.
- 4Decide which material goes where, and why that material fits that job.
Sketch your design
Draw a rough plan here, or use your own notebook. Label the parts.
Build it
These are guides, not rules. Two students can follow them and build very different designs - that is the point.
- 1
Choose your challenge: a water filter, a flood barrier, or a redesign of an everyday object.
- 2
Name your user and the one problem you are solving for them before you build anything.
- 3
Filter: layer materials - cotton, sand, gravel, a coffee filter - inside a cup so water passes through them.
- 4
Flood barrier: shape a wall or channel that keeps water away from a small paper or cardboard house.
- 5
Redesign: study the object, find the one thing that annoys the user, and change just that part.
Testing challenge
A design is only finished when it passes a fair test. Run each test the same way every time.
Water filter - clarity
Pour the same cloudy water through and compare it to the starting container.
Measure: Clearer, a little clearer, or no change
Flood barrier - keep the house dry
Pour a set amount of water against the barrier and check the house behind it.
Measure: Dry, a little wet, or soaked
Product redesign - user test
Have a partner act as the user and try the redesigned object.
Measure: Did it solve their problem? What still needs work?
Record your results
Write down what happens each time you test. Your numbers tell you what to improve. Print this page or copy the table into your notebook.
| Test | What to record | Try 1 | Try 2 | Try 3 |
|---|---|---|---|---|
| Water filter - clarity | Clearer, a little clearer, or no change | |||
| Flood barrier - keep the house dry | Dry, a little wet, or soaked | |||
| Product redesign - user test | Did it solve their problem? What still needs work? |
Improve your design
Your first version is a prototype, not the final answer. Change one thing based on what failed, then test again.
- Filter: if the water is still cloudy, add another layer or a finer material like a coffee filter on top.
- Filter: if it drains too slowly, use coarser layers or a wider container.
- Flood barrier: if water leaked through, seal the gaps or make the wall taller where it failed.
- Redesign: watch where your user got stuck, and fix that one spot.
- Notice the tradeoff - did making it better in one way make it worse in another?
What failed first when you tested it? Pick one to see ways to fix it.
Think about it
- 1Who were you designing for?
- 2What problem did your design solve?
- 3What material worked best?
- 4What tradeoff did you make?
- 5What would you improve for a real user?
Finished early? Try this
- Improve your filter so it also works faster, not just cleaner.
- Design your barrier so it can be reused instead of thrown away.
- Redesign your product to use one less material without losing what makes it work.
Design journal
Jot down your thinking as you work. Your notes are saved on this device only - they are optional and private to you.
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Teacher notes
This lesson connects engineering to fairness and the environment, so give time for the 'who is this for' conversation before building. Reinforce firmly that filtered water is never for drinking. Common mistake: jumping to a solution before naming the user and problem; hold students at the planning step a little longer here.
Running this lesson? The parent & teacher guide has setup, materials prep, safety notes, common failure points, and questions to ask.
Finished building, testing, and reflecting? Mark this lesson complete to track your progress through the 6-lesson course.