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Learning the difference between things that keep their shape and things that flow.
Have you ever wondered why your favorite toy stays the same shape every day, but your morning juice splashes and swirls into any cup you choose?
A solid is something that has its own fixed shape. Think about your favorite teddy bear or a hard rock. If you put a rock inside a lunchbox, does it turn into the shape of the lunchbox? No! It stays exactly like a rock. This is because the tiny bits that make up a solid are packed very tightly together. They are like friends holding hands very tightly—they do not want to move apart. Because they stay put, the solid keeps the same size and shape no matter where you put it.
Let's look at a single pencil. 1. Pick up pencil. 2. Place it inside a round hat. 3. Look at the pencil. Is it still straight? Yes! 4. The pencil is a solid because it did not change into a circle shape to match the hat.
Quick Check
If you move a toy car from a small box to a big box, does the car change its shape?
Answer
No, because the toy car is a solid and solids stay the same shape on their own.
A liquid is very different from a solid. A liquid does not have its own shape. Instead, it is a 'shape-shifter' that takes the shape of whatever container it is in. If you pour water into a square bottle, the water becomes square. If you pour it into a round bowl, it becomes round! This happens because the tiny bits inside a liquid are not holding hands tightly. They can flow and slide past each other. This is why liquids can splash, drip, and run down a hill.
Imagine you have different containers: a tall thin glass and a short wide bowl. 1. Pour orange juice into the tall glass. The juice looks tall and thin. 2. Pour that same juice into the wide bowl. 3. Now the juice looks flat and wide. 4. The juice is a liquid because it changed its shape to fit the bowl.
Quick Check
What is one thing a liquid can do that a solid cannot do?
Answer
A liquid can flow or change its shape to fit a container.
The best way to tell them apart is to ask: 'Does it stay the same or does it flow?' Solids are firm and keep their shape. Liquids are runny and fill the bottom of their container. Even though they are different, we use both every day! We use a solid spoon to eat our liquid soup. We use a solid cup to hold our liquid milk. Understanding how they act helps us choose the right tools for mixing and changing materials.
Can one thing be both a solid and a liquid? 1. Take ice cube. It is hard and keeps its shape. It is a solid. 2. Leave it in the sun for minutes. 3. The ice melts into a puddle of water. 4. Now it can flow and change shape! It has changed from a solid to a liquid.
Which of these is a solid?
What happens to a liquid when you pour it into a new bowl?
A solid can flow just like a liquid.
Review Tomorrow
Tomorrow morning, look at your breakfast. Can you find solids and liquid on the table?
Practice Activity
Go on a 'Shape Hunt' in your kitchen. Find three things that keep their shape (solids) and three things that would splash if you tipped them over (liquids)!