Changing Shapes of Solids
Investigate how the shapes of solid objects can be changed by squashing, bending, twisting, and stretching
What a learner can do afterwards
- Demonstrate four ways to change the shape of a solid: squashing, bending, twisting, stretching
- Compare how different materials respond to these forces (e.g. clay squashes easily, wood does not)
- Explain that the material itself stays the same even when the shape changes
1 · Read
A solid can change its shape without turning into a liquid or a gas. You can squash it, bend it, twist it, or stretch it with your hands.
Zara presses down on a ball of playdough and it flattens into a pancake. She twists a pipe cleaner into a spiral. Then she tries to bend a wooden ruler, but it stays straight and stiff.
Not every material changes shape the same way. Clay and playdough squash easily. Wood is stiff, so it keeps its shape unless you push very hard, and then it might snap instead of bending.
When you squash, bend, twist, or stretch a solid, you only change its shape. The material stays exactly the same. Flattened clay is still clay.
Squashing, bending, twisting, and stretching change a solid's shape, but the material inside always stays the same.
More to read
Rocks are Elastic!! Seeing is Believing
Do you think rocks are always hard and stiff? Try this fun idea. Take a thin, flat piece of marble (a kind of rock) and gently push on it with your hands. Something surprising happens. It bends just a tiny bit, like a stiff piece of plastic!
Most rocks are so thick and heavy that we never see them bend. But when a rock is cut very thin, you can feel it flex a little before it springs back to its own shape.
This shows that even a hard solid like rock reacts to a push or a bend, just not much. Every material responds to squashing and bending in its own way. Squishy clay squashes flat right away. Wood barely bends at all. Thin rock bends just a tiny bit before it stops.
Next time you pick up a rock, remember: it looks solid and still, but if the piece is thin enough, even rock can bend a little.
How to Break in a New Pair of Shoes
New shoes can feel stiff and tight when you first put them on. That's because the material, like leather or canvas, has not been moved around yet. Here are ways people change the shape of their shoes to make them fit better.
Bending: Hold the shoe and gently bend it back and forth where your foot bends when you walk. This softens the stiff spots.
Twisting: Hold the shoe with both hands and twist it gently, like wringing out a towel. This loosens up tight material.
Stretching: Wear thick socks and walk around in the shoes. Your foot slowly stretches the material to fit your shape.
Warming: Some people warm the shoe a little first, because warm material bends and stretches more easily than cold material.
No matter how much you bend, twist, or stretch a shoe, it is still made of the same leather or fabric. Only its shape changes to match your foot better.
2 · Watch
En anglaisTake it off screen
Where it sits
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
23 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.