You will learn
- State the particle model.
- Draw particle diagrams.
- Explain diffusion.
- Explain expansion.
Version 0.2 · expanded edition · built from cited public sources Content is based on the official frameworks and sources listed under Sources and standards. No official endorsement is claimed. Written in the style of common primary school assessments. No exam result is promised.
Student lesson
Words to know
a tiny piece of matter
spreading of particles from high to low concentration
getting bigger when heated
to shake back and forth
1. Discover: The spreading smell
Ama opens a bottle of orange peel essence at the front of the room. Soon the smell reaches the back. “Particles of the smell spread out through the air,” says her teacher. “That is diffusion.”
Think: Would it be faster in a warm room?
2. Understand: Particles
Idea 1: The model
The particle model says matter is made of tiny moving particles. In solids they are tightly packed and vibrate. In liquids they are close but slide. In gases they are far apart and move quickly.
Idea 2: Heating
Heating gives particles more energy. They move faster and push apart, causing expansion.
Idea 3: Diffusion
Particles move from where there are many to where there are few. Diffusion happens fastest in gases and slowest in solids.
3. Worked examples
Example 1 (I show you): Draw
Solid.
- Packed.
- Regular.
- Vibrate.
Answer: Close and regular.
Example 2 (We do it together): Draw
Gas.
- Far apart.
- Fast.
- Random.
Answer: Far apart and random.
Example 3 (You try): Explain
Smell.
Show the steps and answer
- Particles spread.
- Diffusion.
- Warm faster.
Answer: Smell spreads by diffusion.
Did you know?
A single drop of water contains roughly 1.7 sextillion molecules, which is a 17 followed by 20 zeros.
Why this matters
The particle model explains much of chemistry and physics.
4. Explore: Diffusion race
Compare how fast food colouring spreads in warm and cool still water in clear cups.
- Fill two cups.
- Add one drop of colouring.
- Watch both.
- Time the spread.
Think about it: what did you notice?
What did you notice? Colour spread faster in warm water.
5. Practise
Say it in a sentence
Use these starters when you talk about the lesson. Say them out loud.
- A ___ is a tiny piece of matter.
- ___ is the spreading of particles.
- ___ is getting bigger when heated.
- To ___ is to shake back and forth.
Guided practice
Question 1. What is a particle?
Tiny piece.
Question 2. What is diffusion?
Spreading.
Question 3. What is expansion?
Bigger on heating.
Independent practice
Level 1: Start
- What is a particle?
- What is diffusion?
- What is expansion?
- How do solids move?
- How do gases move?
Level 2: Grow
- Why spread?
- Why warm faster?
- Why expansion?
Level 3: Stretch
- Draw diagrams.
- Run the race.
- Explain.
Answers are in the answer key below. Try first, then check.
6. Apply: Science in everyday life
Explain why smell spreads faster in warm air.
Show a sample answer
Use particles.
Another one. Tell a family member one thing from this lesson. Use the words you learned.
Show a sample answer
A clear sentence that uses at least one word from Words to know.
7. Common mistakes
Fix: They vibrate.
Fix: Spaces grow.
8. Lesson summary and revision card
- I can state the particle model.
- I can draw particle diagrams.
- I can explain diffusion.
- I can explain expansion.
9. Check and master
Answer all 14 questions. You will see feedback after each one.
Your result appears here after you answer every question.
10. Key takeaways
- All matter is made of tiny particles.
- Particles move more when heated.
- Solids vibrate; liquids slide; gases move freely.
- Diffusion spreads smells and colours.
11. Next lesson
Next lesson: Mixtures. Keep going with the next idea in this course.
Exam practice
These questions are written in the style of common school and international primary assessments. Try them on your own, without looking back. Then check your answers in the marking guide. The marks are shown in brackets.
- Define particle and diffusion. [2 marks]
- Draw three states. [3 marks]
- Explain a diffusion result. [3 marks]
- Safety rule. [2 marks]
Total: 10 marks.
Marking guide and model answers
- 1 each
- 1 each
- Particles [1]; motion [1]; heat effect [1]
- Any [1]; reason [1]
Score guide: 9 to 10 = secure. 6 to 8 = nearly there, revise the parts you missed. Under 6 = work through the lesson again with a grown-up.
Printable worksheet
- What is a particle?
- What is diffusion?
- What is expansion?
- How do solids move?
- How do gases move?
- Why spread?
- Why warm faster?
- Why expansion?
- Draw diagrams.
- Run the race.
Homework
Draw particle diagrams for ice, water and steam.
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 1. What is a particle? | Tiny piece. | 1 |
| 2. What is diffusion? | Spreading. | 1 |
| 3. What is expansion? | Bigger on heating. | 1 |
| 4. How do solids move? | Vibrate. | 1 |
| 5. How do gases move? | Freely. | 1 |
| 6. Why spread? | Random motion. | 1 |
| 7. Why warm faster? | More energy. | 1 |
| 8. Why expansion? | Push apart. | 1 |
| 9. Draw diagrams. | Diagram. | 1 |
| 10. Run the race. | Table. | 1 |
| Total | 10 |
Independent practice answers. Level 1: 1 Tiny piece.; 2 Spreading.; 3 Bigger on heating.; 4 Vibrate.; 5 Freely.. Level 2: 1 Random motion.; 2 More energy.; 3 Push apart.. Level 3: 1 Diagram.; 2 Table.; 3 Sentence..
Quiz answers: 1 B, 2 C, 3 A, 4 B, 5 C, 6 A, 7 B, 8 C, 9 A, 10 B, 11 C, 12 A, Challenge 1 B, Challenge 2 C.
Mastery and remediation
| Objective | Bronze (Developing) | Silver (Proficient) | Gold (Advanced) |
|---|---|---|---|
| O1 State the particle model | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O2 Draw particle diagrams | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O3 Explain diffusion | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O4 Explain expansion | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
Courseversity badge thresholds (overall quiz score): Gold = 90–100%; Silver = 80–89.9%; Bronze = 70–79.9%. A badge is never a full record of progress.
If a learner struggles
- Find the misconception: “Particles in solids are still.” They vibrate.
- Explain another way: use real objects, pictures or actions first, then words.
- Show a simpler example: Use the particle model.
- Guided practice: work through one example together and let the learner try the next one.
- Reassess: use the quiz again or the worksheet.
- Move on when the learner shows Silver-level evidence independently.
For parents and guardians
In this lesson your child uses the particle model. You do not need to be an expert to help.
- Watch tea colour spread.
- Ask “What are particles doing?”
- Warm water only.
- Ask “how do you know?” after each answer, and listen.
- Praise effort, not only right answers. Mistakes are how we learn.
- Ten to fifteen minutes a day is better than one long session.
Teacher package
1–5. Objectives, prerequisites, materials, preparation, duration
Lesson objectives. Learners will: state the particle model; draw particle diagrams; explain diffusion; explain expansion.
Prerequisite knowledge. Grade 4 ideas: properties of materials, states of matter, melting, freezing, evaporation, dissolving and reversible changes.
Materials. Cups, colouring. Low-resource options: use chalk or charcoal on a board or wall, drawings in the sand, and objects from the classroom instead of printed materials.
Preparation. Warm water.
Suggested duration. 45–60 minutes. It can be split into two shorter sessions.
6–9. Teaching procedure, explanation notes, guided and independent activities
Introduction (5 min). Open a scent and ask, “How did it get to you?”
Explanation (10 min). Teach particles.
Guided activity (10 min). Learners draw.
Independent activity (10 min). Learners test.
Assessment and reflection (5 min). Ask each learner to say one thing they learned and how they know it.
Key questions. How do particles move?
Teacher explanation notes. Start with real objects and safe, hands-on observation. Then talk about what was seen, then draw and write. Always say “how do you know?”. Keep to the safety notes, and use local, safe materials.
10–12. Differentiation, formative assessment, common misconceptions
Support. Use real objects and pictures, short sentences and a partner. Let learners point, show or draw instead of writing. Extension. Ask learners to find a new example at home and explain how they know.
Formative assessment. Listen to learners read and explain, ask “how do you know?”, and check the independent work.
Misconceptions. “Particles in solids are still.” They vibrate.
13–15. Assessment questions, answer keys, marking scheme
Use the quiz, the 10-mark exam practice and the worksheet on this page. All answers and marking guides are in the answer sections above. Re-check every answer before use.
16–19. Remediation, enrichment, homework, teacher reflection
Remediation. Use the particle model. Enrichment. Look for one new example near your home or school, draw it and explain it to someone. Homework. See above.
Teacher reflection. After teaching, record: which ideas learners understood; which misconceptions occurred; which activities worked; which learners need more practice; and what to improve next time.
Sources and standards
This lesson is based on the sources below, and no official endorsement is claimed. Reference starting points: Next Generation Science Standards, Cambridge Primary Science and the IB Primary Years Programme. Where a standard code is named, it points to the official framework.
Research used to shape this lesson. Courseversity Science curriculum, Grade 5 Unit 4, topic 4; Next Generation Science Standards, structure and properties of matter; Cambridge Primary Science Stage 5, chemistry: states of matter and materials; IB Primary Years Programme, how the world works. These sources informed the lesson.