How tough is this stuff?

Have you ever seen a paper skyscraper? Probably not, because paper is not strong enough to withstand the forces acting on a skyscraper. Hold a "tug-push-twist-o'war" to find out which materials can best withstand different forces.

Materials

1. A clear glass or similar see-through container
2. Yarn
3. Popsicle sticks
4. Pipe cleaners
5. Clay
6. Sponges
7. Erasers
8. Rubber bands
9. Paper towel tubes
10. Pencils
11. Cardboard
12. Aluminum foil
13. Drinking straws

Procedure

1. Make a prediction. Before you test the materials, predict which ones will be strongest when you tug, twist or push on it.
2. Try it out. Make a table to record your results. You'll rate each material for each type of stress. Try using the example table and rating scale given below.
3. Tug: To test the material in tension, pull on it from both ends. Record your rating and any observations in the table.
4. Push: To test the material in compression, push it together from both ends. Record your rating and any observations.
5. Twist: To test the material in torsion, twist the two ends in different directions. Record your rating and any observations.
6. Repeat steps 3 through 5 for each material.

Examples

Material	Tension (Tug)	Compression (Push)	Torsion (Twist)
Yarn

Rating Scale

1	Very weak! It crumples or breaks with hardly any force.
2	Only fair - it can't withstand much force.
3	Pretty good - it takes a lot of force to break it.
4	Super strong! We can't break it.

What's Going On?

Which materials were strongest in resisting each type of force? Did any of these results surprise you? Why or why not?

Which materials were strongest across all three tests? How would you describe those materials? Now you can better understand why certain materials are chosen over others when constructing things like buildings, bridges, roads and other things.