Some materials bend. Some do not. A material that bends easily is flexible. A rubber band is flexible. You can stretch it and bend it. It goes back to its shape.
A material that does not bend is rigid. Rigid means stiff. A brick is rigid. A glass cup is rigid too. If you push too hard on a rigid material, it may break instead of bending!
Scientists do a bend test to find out if a material is flexible. They gently bend the material and watch what happens. Does it bend? Does it snap back? Does it stay bent? Or does it break?
Both properties are useful. A jump rope must be flexible. A ladder must be rigid. Today you will do your own bend tests!
1. What do we call a material that bends easily?
2. What does rigid mean?
3. What can happen if you push too hard on a rigid material?
4. Why must a ladder be rigid and not flexible?
Write what each word means in your own words.
Circle the answer for each object.
| Object | Flexible or rigid? |
|---|---|
| A rubber band | FLEXIBLE / RIGID |
| A brick | FLEXIBLE / RIGID |
| A shoelace | FLEXIBLE / RIGID |
| A drinking glass | FLEXIBLE / RIGID |
| A garden hose | FLEXIBLE / RIGID |
| A wooden ruler | FLEXIBLE / RIGID |
Write T for true or F for false in each circle.
Draw something flexible, something rigid, and something with both parts (like a shovel).
1. Why is a bike tire flexible but the bike frame rigid?
1. A material that bends easily is ______________ .
2. A material that does not bend is ______________ .
3. Rigid materials feel ______________ when you push them.
4. Scientists do a bend ______________ to check flexibility.
5. If you push a rigid material too hard, it might ______________ .
6. It is easy to ______________ a pipe cleaner into a circle.
Only bend safe things a grown-up gives you. Never bend glass or anything sharp. Wear shoes in case something snaps and drops.
You need: a straw, a piece of paper, a rubber band, and a small dry stick or twig.
Gently bend each item. Watch closely. Circle what happens to each one.
| Material | What happened when I bent it? |
|---|---|
| Straw | BENT / SNAPPED BACK / BROKE |
| Paper | BENT / SNAPPED BACK / BROKE |
| Rubber band | BENT / SNAPPED BACK / BROKE |
| Dry stick | BENT / SNAPPED BACK / BROKE |
The most flexible material was: ______________________
The most rigid material was: ______________________
You will build a bridge and test which materials make it strong! Save your straws and paper.
| I learned... | Circle one |
|---|---|
| What flexible means | YES / NOT YET |
| What rigid means | YES / NOT YET |
| How to do a bend test | YES / NOT YET |