| # | What makes it strong? | Why does this help? |
|---|---|---|
| 1 | ||
| 2 | ||
| 3 |
Standard: Fill in the definition. | Support: Definitions shown in grey — read and copy into your folio. | Extension: Use each term in a sentence.
| Term | Definition | Use in a sentence (Extension) |
|---|---|---|
| Design brief | A document outlining the problem, specifications and constraints |
|
| Specification | A detailed requirement the solution MUST meet |
|
| Constraint | A limitation or restriction on design, e.g. materials, time, cost |
|
| Truss | A framework of beams or sticks forming triangles for strength |
|
| Triangulation | Using triangles in a structure to make it rigid and strong |
|
| Span | The distance a bridge covers between its two supports |
|
| Load capacity | The maximum weight a structure can support before failure |
⚠ YOUR CHALLENGE
Design and construct a truss bridge from craft sticks and PVA glue that can span 30–40 cm and support the maximum load possible.
| Specification | Requirement |
|---|---|
| Materials | Craft sticks + PVA glue only |
| Span | 30–40 cm between supports |
| Structure | Must include triangulation |
| Freestanding | No tape or attachment to supports |
In your own words, describe what you need to do:
Craft sticks are made from birch wood. Understanding the material helps you design a stronger bridge.
Standard craft stick: 11.4 cm × 1 cm × 2 mm (birch)
Grain direction: Strong along the length, weak across the width
PVA tips: Thin, even layer on BOTH surfaces. Let dry fully for strongest bond.
| Property | Your observation / notes |
|---|---|
| Stick dimensions (L × W × H) | |
| Material type | |
| Strongest direction | |
| Weakest direction | |
| Glue type and best practice |
There are two main ways to join craft sticks. Study both and compare.
| Joint Type | Description | Draw the joint |
|---|---|---|
| Butt joint | Ends of two sticks pushed together and glued. Quick but weaker. | |
| Lap joint | Sticks overlap by 1–2 cm and are glued flat. Stronger bond, more surface area. |
Which joint is stronger and why?
Write a full design brief for your bridge project. Include all four sections.
Find 3 different real truss bridges. Record the details in the table below.
| Bridge name & location | Truss type (Warren / Pratt / Howe / other) | What makes it strong? | One thing to adapt for my design |
|---|---|---|---|
For each bridge you researched, list the Plus (good), Minus (bad), and Interesting aspects.
| Bridge | Plus (+) | Minus (−) | Interesting (?) |
|---|---|---|---|
Draw 3 different bridge design ideas. Annotate each sketch with labels and notes.
Sketch 1:
Sketch 2:
Sketch 3:
➤ Circle your BEST design. Which one did you choose and WHY?
Write a numbered list of the steps you will follow to build your bridge.
| Step | What I will do |
|---|---|
| 1 | |
| 2 | |
| 3 | |
| 4 | |
| 5 | |
| 6 | |
| 7 | |
| 8 |
Use these sentence starters to help you write your design brief:
Load-to-weight ratio target: Calculate a target ratio for your bridge.
Advanced truss research: Research a K-truss or modified Warren truss. How does it differ from a standard truss?
Cost constraint challenge: If each stick costs $1 and glue costs $5, write a budget for your bridge.
Formal engineering language: Rewrite your specifications using formal engineering language.
| Success Criteria | Got it 🟢 | Nearly there 🟠 | Need help 🔴 |
|---|---|---|---|
| I can write a clear design brief with specifications | |||
| I can research 3 real bridges for inspiration | |||
| I can create at least 3 thumbnail sketches with annotations | |||
| I can plan my construction approach |