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🗂️ Grouping Solids, Liquids, and Gases

Become a state-of-matter detective! Learn the clear rules for grouping anything as a solid, liquid, or gas, even the tricky ones like sand and jelly.

3
lessons
~15 min
to learn
🔬 Science
subject
Ages 6–12
level
Start the course →

What you’ll learn

  1. The Rules for Each StateUse fixed shape and fixed size to group materials as solid, liquid, or gas.A solid keeps its shape and size, a liquid keeps its size but takes the container's shape, and a gas has no fixed shape or size and fills any space. A flowchart of yes-or-no questions about shape and space names the state every time.
  2. Tricky OnesExplain why powders are solids and how to spot invisible gases.Powders like sand, sugar, and flour pour, but each grain is a tiny solid that keeps its shape, so they are solids. Some gases, like air, are invisible, but if something spreads out to fill a space, it is a gas even when you cannot see it.
  3. Grouping PracticeConfidently group a range of materials, avoiding common state mix-ups.Using the clues about shape and space, we can group any material and avoid being fooled. Powders are solids, liquids take the container's shape while keeping their size, and gases spread to fill space. Sorting and matching practice locks in the rules.

Questions this course answers

Which state keeps BOTH its own shape and its size?

A solid keeps its own shape and its size no matter what container it is in.

How is a gas different from a solid and a liquid?

A gas has no fixed size and spreads out to fill whatever space it is in, unlike a solid or liquid.

Using the flowchart, what is something that does NOT keep its shape but DOES keep its amount?

Something that loses its shape but keeps its amount takes the container's shape while keeping its size, which is a liquid.

Sand pours like a liquid. What state is it really?

Sand is a solid, because every single grain is a tiny solid that keeps its own shape, even though the pile pours.

You cannot see the air. How can you tell it is a gas?

Air spreads out to fill whatever space it is in, like puffing up a balloon, which is how we know it is a gas.

Which group does flour belong in?

Flour is a solid, because it is a powder made of many tiny solid grains, even though it pours.

Grounded in trusted sources

  • BBC Bitesize
  • Britannica Kids
  • Royal Society of Chemistry

Every Wunder lesson is built from real, reputable sources — never invented.

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