You will learn
- Recall particle theory.
- Use the model.
- Distinguish changes.
- Solve simple density problems.
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
all matter is made of tiny moving particles
mass per unit volume
two or more elements joined chemically
substances mixed but not joined chemically
1. Discover: The mystery liquids
Three clear liquids sit in identical cups. Ms Asare asks, “How can we tell them apart without tasting?” The class weighs equal volumes and calculates density to identify water, salt water and cooking oil.
Think: Which liquid will have the highest density?
2. Understand: Matter
Idea 1: Particles
All matter is made of tiny particles in constant motion. Solids are packed in fixed positions, liquids are close but slide past each other, and gases are far apart and move freely. Heating makes particles move faster.
Idea 2: Density
Density = mass ÷ volume. Water is about 1 g/cm³; oil is less (it floats); salt water is more. Density is a property that helps identify materials.
Idea 3: Changes
Physical changes (melting, dissolving) can be reversed; chemical changes (rusting, burning) make new substances. An element is one kind of atom, a compound joins elements, and a mixture can be separated physically.
3. Worked examples
Example 1 (I show you): Calculate
Density.
- Mass.
- Volume.
- Divide.
Answer: g/cm³.
Example 2 (We do it together): Classify
Change.
- Melting.
- Burning.
- Dissolving.
Answer: Physical or chemical.
Example 3 (You try): Explain
Particles.
Show the steps and answer
- Solid.
- Liquid.
- Gas.
Answer: Spacing.
Did you know?
The densest naturally occurring element, osmium, is about 22.6 times denser than water.
Why this matters
The particle model is the starting point for secondary chemistry.
4. Explore: Density detectives
Measure the mass and volume of three safe samples (water, salt solution, vegetable oil) using a balance and measuring cylinder, calculate density and identify each.
- Measure mass.
- Measure volume.
- Calculate.
- Identify.
Think about it: what did you notice?
What did you notice? Oil had the lowest density, so it floats.
5. Practise
Say it in a sentence
Use these starters when you talk about the lesson. Say them out loud.
- ___ theory says all matter is made of particles.
- ___ is mass per unit volume.
- A ___ is two or more elements joined chemically.
- A ___ is substances mixed but not joined chemically.
Guided practice
Question 1. Density formula?
Mass ÷ volume.
Question 2. Solid particles?
Packed.
Question 3. Gas particles?
Far apart.
Independent practice
Level 1: Start
- Density formula?
- Solid particles?
- Gas particles?
- Burning is?
- Melting is?
Level 2: Grow
- Why oil floats?
- Why heat speeds?
- Why mixtures separate?
Level 3: Stretch
- Measure.
- Calculate.
- Explain.
Answers are in the answer key below. Try first, then check.
6. Apply: Science in everyday life
Explain why oil floats on water.
Show a sample answer
Use density.
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: Different.
Fix: Still move.
8. Lesson summary and revision card
- I can recall particle theory.
- I can use the model.
- I can distinguish changes.
- I can solve simple density problems.
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
- Matter is made of particles.
- States differ in spacing and motion.
- Density = mass ÷ volume.
- Chemical changes make new substances.
11. Next lesson
Next lesson: Forces and energy review. 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 density and compound. [2 marks]
- Calculate a density. [3 marks]
- Explain physical and chemical change. [3 marks]
- Safety rule. [2 marks]
Total: 10 marks.
Marking guide and model answers
- 1 each
- Formula [1]; substitution [1]; answer with unit [1]
- Physical [1]; chemical [1]; example [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
- Density formula?
- Solid particles?
- Gas particles?
- Burning is?
- Melting is?
- Why oil floats?
- Why heat speeds?
- Why mixtures separate?
- Measure.
- Calculate.
Homework
Find the density of a safe object at home.
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 1. Density formula? | Mass ÷ volume. | 1 |
| 2. Solid particles? | Packed. | 1 |
| 3. Gas particles? | Far apart. | 1 |
| 4. Burning is? | Chemical. | 1 |
| 5. Melting is? | Physical. | 1 |
| 6. Why oil floats? | Less dense. | 1 |
| 7. Why heat speeds? | Energy. | 1 |
| 8. Why mixtures separate? | Not joined. | 1 |
| 9. Measure. | Table. | 1 |
| 10. Calculate. | Numbers. | 1 |
| Total | 10 |
Independent practice answers. Level 1: 1 Mass ÷ volume.; 2 Packed.; 3 Far apart.; 4 Chemical.; 5 Physical.. Level 2: 1 Less dense.; 2 Energy.; 3 Not joined.. Level 3: 1 Table.; 2 Numbers.; 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 Recall particle theory | 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 Use the 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 |
| O3 Distinguish changes | 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 Solve simple density problems | 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: “A mixture is a compound.” Different.
- 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 revises matter and density. You do not need to be an expert to help.
- Float an object in water.
- Ask “Why does it float?”
- Wipe spills.
- 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: recall particle theory; use the model; distinguish changes; solve simple density problems.
Prerequisite knowledge. Grade 6 ideas: Units 1 to 11 of Grade 6 Science.
Materials. Balance, measuring cylinder, liquids. 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. Label samples.
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). Show three clear liquids and ask, “How do we tell them apart?”
Explanation (10 min). Teach the review.
Guided activity (10 min). Learners measure.
Independent activity (10 min). Learners calculate.
Assessment and reflection (5 min). Ask each learner to say one thing they learned and how they know it.
Key questions. How do particles explain this?
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. “A mixture is a compound.” Different.
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 6 Unit 12, topic 4; Next Generation Science Standards, science and engineering practices; Cambridge Lower Secondary Science, thinking and working scientifically; IB Primary Years Programme, how we express ourselves. These sources informed the lesson.