You will learn
- State that light travels in straight lines.
- Test with aligned cards.
- Use ray diagrams.
- Explain shadows with straight rays.
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
- Light travels in straight lines.
- We show light paths as rays.
- Light cannot bend around objects.
- Blocked light makes shadows.
Words to know
a line showing the path of light
not bending
a stream of light
to stop light passing
1. Discover: The hole test
Naana lines up three cards with holes. She shines a torch through the first hole. Light shines through all three. When she moves the middle card sideways, the light stops. “The holes must be in a straight line,” she says.
Think: What does this show about light?
2. Understand: Straight lines
Idea 1: Rays
We draw a ray as a straight line with an arrow to show the path of light. A beam is many rays together.
Idea 2: The card test
Light passes through aligned holes but is stopped if one card moves. This shows that light travels straight and cannot bend around corners.
Idea 3: Blocked light
When an object blocks the rays, a dark area, a shadow, forms behind it. Straight rays explain why shadows have the same shape as the object.
3. Worked examples
Example 1 (I show you): Predict
Cards aligned.
- Light passes.
- Straight path.
- Bright spot.
Answer: Light passes through all.
Example 2 (We do it together): Predict
Move a card.
- Path blocked.
- No light.
- Dark.
Answer: No light passes.
Example 3 (You try): Draw
A torch to a wall.
Show the steps and answer
- Draw a line.
- Add an arrow.
- Straight.
Answer: Rays are straight lines with arrows.
Did you know?
Ancient builders used the straight path of light to line up temples with sunrises on special days.
Why this matters
Knowing light travels straight helps us explain shadows, mirrors and cameras.
4. Explore: Card and torch test
Line up three cards with holes to test whether light travels in a straight line.
- Punch holes in the middle of three cards.
- Stand them in a row.
- Shine a torch through the holes.
- Move a card and observe.
Think about it: what did you notice?
What did you notice? Light passed only when the holes lined up.
5. Practise
Say it in a sentence
Use these starters when you talk about the lesson. Say them out loud.
- A ___ is a path of light.
- Light travels in ___ lines.
- A ___ is many rays together.
- Objects ___ light.
Guided practice
Question 1. How does light travel?
Straight.
Question 2. What is a ray?
Light path.
Question 3. What is a beam?
Many rays.
Independent practice
Level 1: Start
- How does light travel?
- What is a ray?
- What is a beam?
- What is blocked light?
- What can light not do?
Level 2: Grow
- Why do cards need aligning?
- Why shadows?
- Why arrows?
Level 3: Stretch
- Draw rays.
- Run the card test.
- Explain results.
Answers are in the answer key below. Try first, then check.
6. Apply: Science in everyday life
Explain why you cannot see around a corner.
Show a sample answer
Use light rays.
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: It travels straight.
Fix: Straight with arrows.
8. Lesson summary and revision card
- I can state that light travels in straight lines.
- I can test with aligned cards.
- I can use ray diagrams.
- I can explain shadows with straight rays.
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
- Light travels in straight lines.
- We show light paths as rays.
- Light cannot bend around objects.
- Blocked light makes shadows.
11. Next lesson
Next lesson: Reflection. 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.
- State how light travels. [1 mark]
- Describe the card test. [3 marks]
- Draw and label a ray. [2 marks]
- Explain shadows using rays. [3 marks]
- Safety rule? [1 mark]
Total: 10 marks.
Marking guide and model answers
- Straight lines [1]
- Three cards [1]; torch [1]; move a card [1]
- Straight line [1]; arrow [1]
- Light blocked [1]; straight [1]; dark area [1]
- Any [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
- How does light travel?
- What is a ray?
- What is a beam?
- What is blocked light?
- What can light not do?
- Why do cards need aligning?
- Why shadows?
- Why arrows?
- Draw rays.
- Run the card test.
Homework
Use a torch and a cup to show light is straight, with adult help.
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 1. How does light travel? | Straight. | 1 |
| 2. What is a ray? | Light path. | 1 |
| 3. What is a beam? | Many rays. | 1 |
| 4. What is blocked light? | Shadow. | 1 |
| 5. What can light not do? | Bend corners. | 1 |
| 6. Why do cards need aligning? | Straight path. | 1 |
| 7. Why shadows? | Light blocked. | 1 |
| 8. Why arrows? | Direction. | 1 |
| 9. Draw rays. | Diagram. | 1 |
| 10. Run the card test. | Table. | 1 |
| Total | 10 |
Independent practice answers. Level 1: 1 Straight.; 2 Light path.; 3 Many rays.; 4 Shadow.; 5 Bend corners.. Level 2: 1 Straight path.; 2 Light blocked.; 3 Direction.. 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 that light travels in straight lines | 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 Test with aligned cards | 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 Use ray 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 |
| O4 Explain shadows with straight rays | 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: “Light bends around corners.” It travels straight.
- Explain another way: use real objects, pictures or actions first, then words.
- Show a simpler example: Explain straight-line light with rays.
- 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 tests that light travels straight. You do not need to be an expert to help.
- Play with a torch and a wall.
- Ask “Can light bend?”
- Do not shine into eyes.
- 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 that light travels in straight lines; test with aligned cards; use ray diagrams; explain shadows with straight rays.
Prerequisite knowledge. Grade 3 physical ideas: forces, materials, and how to measure and record in fair tests.
Materials. Cards, torch, adult hole-punch. 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. Adult punches the cards.
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). Shine a torch on a wall and ask, “How does the light travel?”
Explanation (10 min). Teach rays.
Guided activity (10 min). Learners test.
Independent activity (10 min). Learners draw.
Assessment and reflection (5 min). Ask each learner to say one thing they learned and how they know it.
Key questions. Straight? What does blocking do?
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. “Light bends around corners.” It travels straight.
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 straight-line light with rays. 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 2; 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.