🌉 Introduction: Why Test Bridge Materials?

Engineers must test different materials to build safe, strong bridges. When vehicles cross a bridge, forces push down (compression) and pull apart (tension) the bridge materials. Testing helps us choose the best materials that won't break under heavy loads.

Your Investigation: You will test four materials - wood, plastic, metal, and cardboard - to see which can hold the most weight before breaking or bending significantly.

Data Collection Table

Material Type	Weight Applied (grams)	Observations (bending, breaking, etc.)
Wood
Plastic
Metal
Cardboard

📝 Investigation Questions

Level 1: Observation Questions

1. Which material held the most weight before breaking?

2. Which material broke or bent first?

3. What happened to the cardboard when weight was added?

It stayed completely straight

It bent or sagged

It became stronger

Level 2: Reasoning Questions

4. Explain why some materials are stronger than others for bridge building.

5. If you were building a real bridge, which material would you choose and why?

🔬 Level 3: Analysis & Design

6. Calculate the strength-to-weight ratio for each material. If the wood sample weighed 50g and held 800g, its ratio is 800÷50 = 16. Complete the calculations below:

7. Design a bridge using two different materials. Draw your design and explain why you chose each material for different parts of the bridge.

8. Predict what would happen if you tested the materials in different weather conditions (hot, cold, wet). Explain your reasoning.