Solids, Liquids and Gases: The Particle Model — Answers
Answer sheet with model answers and success criteria for the Year 5 states of matter & materials worksheet.
Success TutoringWorksheetsAnswer sheetYear 5 · Science · States of Matter & MaterialsSolids, Liquids and Gases: The Particle Model — Answers
Part A: Thinking with particles
Read the passage. Then circle the best answer.
All matter is made of particles far too small to see, even with a normal microscope. How the particles are arranged and how they move explains how solids, liquids and gases behave.
Solids: particles are packed tightly in a regular pattern and only vibrate in place. Solids keep their own shape and volume.
Liquids: particles are still close together but can slide past each other. Liquids flow, take the shape of their container and keep the same volume.
Gases: particles are far apart and move quickly in all directions. Gases spread out to fill any container and can be squashed (compressed).
Heating gives particles more energy, so they move faster. That is why heating can melt a solid or evaporate a liquid. The particles themselves do not grow bigger — they just move more and spread further apart.
- Aare far apart and move fast
- Bare packed tightly and vibrate in place
- Cslide past each other
- Ddo not move at all
Answer: are packed tightly and vibrate in place
Solid particles are held tightly in place. They cannot swap places, but they do vibrate (jiggle).
- AIts particles are far apart.
- BIts particles are fixed in place.
- CIts particles can slide past each other.
- DIts particles get bigger.
Answer: Its particles can slide past each other.
Liquid particles are close together but can move past one another, so the liquid flows to fill the bottom of its container.
- Asolid
- Bliquid
- Cgas
- Dnone of them
Answer: gas
Gas particles have lots of empty space between them, so they can be pushed closer together.
- Again energy and start to move past each other
- Bget bigger
- Cdisappear
- Dstop moving
Answer: gain energy and start to move past each other
Heating gives the particles more energy. They break free of their fixed places and can slide around — the solid becomes a liquid.
- Aare heavy and sink
- Bstay in one place
- Care packed tightly together
- Dmove quickly in all directions and spread out
Answer: move quickly in all directions and spread out
Gas particles move fast and randomly, so they spread out to fill the whole space.
Part B: Explaining properties
- solid
- liquid
- gas
- packed tightly, vibrate in place
- far apart, move fast in all directions
- close together, slide past each other
Answer: solid → packed tightly, vibrate in place; liquid → close together, slide past each other; gas → far apart, move fast in all directions
Answer: evaporation
Also accept: evaporating or boiling.
Answer: The particles in wood are held tightly in place, so it keeps its shape. The particles in juice can slide past each other, so it flows and takes the shape of its container.
Part C: True or false?
Write True or False.
Answer: False
The particles stay the same size. They move faster and spread a little further apart, so the rod expands slightly.
Answer: True
Liquid particles stay close together, so 200 mL stays 200 mL whatever the container shape.
Answer: False
Solid particles vibrate in place all the time; they just cannot move past each other.
Answer: True
Air is a mixture of gases, and gases are made of particles.
Part D: Working scientifically: squash test
You can try this with a medicine syringe from a pharmacy. Never use a syringe with a needle.
Sam filled one plastic syringe (no needle) with air and another with water. He blocked the end of each with his finger and pushed the plunger.
Answer: The plunger moved in — the air was squashed into a smaller space.
Answer: The plunger hardly moved — the water could not be squashed.
Model answer: Air is a gas. Its particles are far apart with lots of empty space, so pushing the plunger moves them closer together. Water is a liquid. Its particles are already touching, so there is almost no space to push them into.
Success criteria:
- Identifies air as a gas and water as a liquid
- Explains that gas particles have space between them
- Explains that liquid particles are already close together
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.
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