You will learn
- Explain why we use models.
- Build a scale model.
- Compare size and distance.
- State limits of a model.
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
- Models help us study big or distant things.
- A scale model keeps sizes in proportion.
- Earth is about four times wider than the Moon.
- Every model has limits.
Words to know
a copy or picture that helps us understand
the ratio between model and real size
the distance across a circle through the centre
a way a model is not accurate
1. Discover: The ball model
Fiifi holds a football to stand for Earth and a tennis ball for the Moon. “The Moon is smaller,” he says. His teacher asks him to stand the Moon in the right place. Fiifi walks and walks. “It has to be nine metres away!” he says. “Space is mostly empty.”
Think: Why does a model help?
2. Understand: Models
Idea 1: Why models?
Earth and the Moon are too big and far to see all at once. A model shows them small enough to study.
Idea 2: Scale
A scale model keeps the right ratio. Earth’s diameter is about four times the Moon’s. With a 22 cm ball for Earth, the Moon is about a 6 cm ball, 6.6 metres away.
Idea 3: Limits
Every model has a limitation: it may not show movement, colour or true distance. Scientists test models and improve them.
3. Worked examples
Example 1 (I show you): Compare
Earth and Moon.
- Earth is bigger.
- About four times.
- Ratio.
Answer: Earth is about four times wider.
Example 2 (We do it together): Scale
Earth 22 cm.
- Moon about 6 cm.
- Distance 6.6 m.
- Ratio.
Answer: The Moon is about 6 cm and 6.6 m away.
Example 3 (You try): Limit
Model lacks gravity.
Show the steps and answer
- Does not move.
- Not real.
- Limits.
Answer: Models cannot show everything.
Did you know?
On the same scale as a 22 cm Earth, the Sun would be a ball about 24 metres across and 2.5 kilometres away.
Why this matters
Models let us understand things that are too big, small or far to see.
4. Explore: Scale model
Make a scale model of Earth and Moon using balls and a long measuring tape.
- Choose balls in the ratio 4:1.
- Measure the distance.
- Place them apart.
- Walk the distance.
Think about it: what did you notice?
What did you notice? The distance was far greater than expected.
5. Practise
Say it in a sentence
Use these starters when you talk about the lesson. Say them out loud.
- A ___ is a copy that helps understanding.
- A ___ keeps sizes in the right ratio.
- A ___ is the distance across a circle.
- A ___ is a way a model is not accurate.
Guided practice
Question 1. What is a model?
A copy.
Question 2. What is scale?
Ratio.
Question 3. What is diameter?
Across circle.
Independent practice
Level 1: Start
- What is a model?
- What is scale?
- What is diameter?
- What is limitation?
- How big is Earth vs Moon?
Level 2: Grow
- Why scale?
- Why limits?
- Why measure distance?
Level 3: Stretch
- Build a model.
- Measure distance.
- List limits.
Answers are in the answer key below. Try first, then check.
6. Apply: Science in everyday life
Explain a limit of the Earth-Moon model.
Show a sample answer
Example.
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 simplify.
Fix: It is far.
8. Lesson summary and revision card
- I can explain why we use models.
- I can build a scale model.
- I can compare size and distance.
- I can state limits of a model.
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
- Models help us study big or distant things.
- A scale model keeps sizes in proportion.
- Earth is about four times wider than the Moon.
- Every model has limits.
11. Next lesson
Next lesson: Earth–Sun–Moon relationships. 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 model and scale. [2 marks]
- Describe the Earth-Moon scale model. [3 marks]
- State two limitations. [2 marks]
- Safety rule. [3 marks]
Total: 10 marks.
Marking guide and model answers
- 1 each
- Balls [1]; ratio [1]; distance [1]
- 1 each
- Any [1]; reason [1]; extra [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 model?
- What is scale?
- What is diameter?
- What is limitation?
- How big is Earth vs Moon?
- Why scale?
- Why limits?
- Why measure distance?
- Build a model.
- Measure distance.
Homework
Make a scale model of Earth and Moon at home with balls.
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 1. What is a model? | A copy. | 1 |
| 2. What is scale? | Ratio. | 1 |
| 3. What is diameter? | Across circle. | 1 |
| 4. What is limitation? | Not accurate. | 1 |
| 5. How big is Earth vs Moon? | Four times. | 1 |
| 6. Why scale? | Keep proportion. | 1 |
| 7. Why limits? | Cannot show all. | 1 |
| 8. Why measure distance? | Realistic. | 1 |
| 9. Build a model. | Model. | 1 |
| 10. Measure distance. | Number. | 1 |
| Total | 10 |
Independent practice answers. Level 1: 1 A copy.; 2 Ratio.; 3 Across circle.; 4 Not accurate.; 5 Four times.. Level 2: 1 Keep proportion.; 2 Cannot show all.; 3 Realistic.. Level 3: 1 Model.; 2 Number.; 3 List..
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 Explain why we use models | 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 Build a scale 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 Compare size and distance | 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 State limits of a 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 |
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: “Models are exact copies.” They simplify.
- Explain another way: use real objects, pictures or actions first, then words.
- Show a simpler example: Build and judge models.
- 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 builds a scale model. You do not need to be an expert to help.
- Use balls and a hallway.
- Ask “How far is the Moon?”
- Respect safe space.
- 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: explain why we use models; build a scale model; compare size and distance; state limits of a model.
Prerequisite knowledge. Grade 3 Earth ideas: weather patterns, seasons and shadows.
Materials. Balls, tape measure. 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. Clear a pathway.
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). Hold up two balls and ask, “How far apart are they?”
Explanation (10 min). Teach models.
Guided activity (10 min). Learners build.
Independent activity (10 min). Learners discuss limits.
Assessment and reflection (5 min). Ask each learner to say one thing they learned and how they know it.
Key questions. Right ratio? What is missing?
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. “Models are exact copies.” They simplify.
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. Build and judge models. 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 4 Unit 8, topic 9; Next Generation Science Standards, Earth’s place in the universe; Cambridge Primary Science Stage 4, Earth and space; IB Primary Years Programme, where we are in place and time. These sources informed the lesson.