You will learn
- Predict shadow size changes.
- Measure shadow length.
- Explain how source position changes shadows.
- Link to the Sun and time of day.
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
how far apart two things are
how long something is
clearly outlined
where something is
1. Discover: The growing shadow
Selorm holds a toy close to a torch and its shadow on the wall is huge. When she moves the toy farther from the torch, the shadow shrinks. “Shadows change with distance,” she records. Later she places the torch low on the table and the shadow stretches long.
Think: What made the shadow change?
2. Understand: Shadow changes
Idea 1: Distance and size
The nearer an object is to the light source, the larger its shadow. Moving it away makes the shadow smaller. Measure with a ruler and compare.
Idea 2: Source position
A low position of the source makes a longer shadow; a high source makes a shorter one. This explains why shadows are long in the morning and evening.
Idea 3: Sharpness
Shadows are sharp when the source is small and the object is close to the screen; they are fuzzy when the object is far from the screen.
3. Worked examples
Example 1 (I show you): Predict
Move object toward torch.
- Bigger.
- Closer to source.
- Larger shadow.
Answer: The shadow gets larger.
Example 2 (We do it together): Predict
Lower the torch.
- Longer.
- Low source.
- Stretched.
Answer: The shadow gets longer.
Example 3 (You try): Measure
Shadow 20 cm vs 10 cm.
Show the steps and answer
- Measure both.
- Difference 10 cm.
- Longer first.
Answer: The first shadow is 10 cm longer.
Did you know?
Sundials use the changing length and direction of a shadow to tell the time, a method humans used more than 3,000 years ago.
Why this matters
Shadow changes explain how sundials work and why shadows lengthen in the evening.
4. Explore: Measure shadows
Measure the shadow of a toy at five distances from a torch.
- Place a toy 10 cm from the torch.
- Measure the shadow height.
- Move it 10 cm farther each time.
- Record and graph the results.
Think about it: what did you notice?
What did you notice? The shadow got smaller as the toy moved away.
5. Practise
Say it in a sentence
Use these starters when you talk about the lesson. Say them out loud.
- ___ is how far apart two things are.
- ___ is how long something is.
- A ___ shadow has clear edges.
- ___ is where something is.
Guided practice
Question 1. Closer gives?
Bigger shadow.
Question 2. Farther gives?
Smaller shadow.
Question 3. Low source gives?
Long shadow.
Independent practice
Level 1: Start
- Closer gives?
- Farther gives?
- Low source gives?
- High source gives?
- What is sharp?
Level 2: Grow
- Why morning shadows long?
- Why sharper near screen?
- Why measure?
Level 3: Stretch
- Measure five distances.
- Graph shadow height.
- Explain the pattern.
Answers are in the answer key below. Try first, then check.
6. Apply: Science in everyday life
Explain why shadows are long in the evening.
Show a sample answer
Use the Sun’s position.
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 change.
Fix: Smaller.
8. Lesson summary and revision card
- I can predict shadow size changes.
- I can measure shadow length.
- I can explain how source position changes shadows.
- I can link to the Sun and time of day.
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
- Moving the object nearer the source makes a larger shadow.
- A lower source makes a longer shadow.
- Shadows are sharper when the object is near the screen.
- The Sun moves so shadows change.
11. Next lesson
Next lesson: Light investigations. 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.
- Predict the effect of moving an object nearer. [2 marks]
- Describe how to measure shadows. [3 marks]
- Explain why shadows lengthen in the evening. [3 marks]
- Safety rule? [2 marks]
Total: 10 marks.
Marking guide and model answers
- Larger [1]; closer to source [1]
- Torch and toy [1]; distances [1]; ruler [1]
- Sun low [1]; rays slanted [1]; longer [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
- Closer gives?
- Farther gives?
- Low source gives?
- High source gives?
- What is sharp?
- Why morning shadows long?
- Why sharper near screen?
- Why measure?
- Measure five distances.
- Graph shadow height.
Homework
Measure your own shadow three times in the day (not looking at the Sun).
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 1. Closer gives? | Bigger shadow. | 1 |
| 2. Farther gives? | Smaller shadow. | 1 |
| 3. Low source gives? | Long shadow. | 1 |
| 4. High source gives? | Short shadow. | 1 |
| 5. What is sharp? | Clear edges. | 1 |
| 6. Why morning shadows long? | Low Sun. | 1 |
| 7. Why sharper near screen? | Less blur. | 1 |
| 8. Why measure? | Compare. | 1 |
| 9. Measure five distances. | Table. | 1 |
| 10. Graph shadow height. | Graph. | 1 |
| Total | 10 |
Independent practice answers. Level 1: 1 Bigger shadow.; 2 Smaller shadow.; 3 Long shadow.; 4 Short shadow.; 5 Clear edges.. Level 2: 1 Low Sun.; 2 Less blur.; 3 Compare.. Level 3: 1 Table.; 2 Graph.; 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 Predict shadow size 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 |
| O2 Measure shadow length | 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 how source position changes shadows | 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 Link to the Sun and time of day | 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: “Shadows do not change.” They change.
- Explain another way: use real objects, pictures or actions first, then words.
- Show a simpler example: Explain how shadows change.
- 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 measures shadow changes. You do not need to be an expert to help.
- Trace shadows at different times.
- Ask “Why is it longer?”
- Never look at the Sun.
- 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: predict shadow size changes; measure shadow length; explain how source position changes shadows; link to the Sun and time of day.
Prerequisite knowledge. Grade 3 physical ideas: forces, materials, and how to measure and record in fair tests.
Materials. Torch, ruler, toy. 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. Set up a dark corner.
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). Move a toy and ask, “What changed?”
Explanation (10 min). Teach shadow changes.
Guided activity (10 min). Learners measure.
Independent activity (10 min). Learners graph.
Assessment and reflection (5 min). Ask each learner to say one thing they learned and how they know it.
Key questions. What changed the shadow?
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. “Shadows do not change.” They change.
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. Explain how shadows change. 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 4, topic 9; Next Generation Science Standards, waves and their applications (light); Cambridge Primary Science Stage 4, physics: light and dark; IB Primary Years Programme, how the world works. These sources informed the lesson.