Light
KS2SC-KS2-D005
Physics domain covering light sources, reflection, shadows and Sun safety (Y3), progressing to light travelling in straight lines, how we see objects, and explanations of shadows (Y6). Taught in Y3 and revisited with deeper explanation in Y6.
National Curriculum context
The Light domain at KS2 requires pupils to understand light as a physical phenomenon — how it is produced, how it travels and how it interacts with materials. Pupils discover that light travels in straight lines and that we see because light enters the eye, correcting common misconceptions from younger years. The statutory curriculum requires pupils to investigate how shadows are formed and how their size and shape relate to the position of the light source, and to understand reflection as the mechanism by which mirrors and smooth surfaces change the direction of light. Pupils also explore how light is refracted, providing the conceptual foundation for understanding how lenses and optical instruments work.
4
Concepts
2
Clusters
1
Prerequisites
4
With difficulty levels
Lesson Clusters
Investigate light sources, vision, and the formation of shadows
introduction CuratedLight and vision (we need light to see) and shadow formation (light blocked by opaque objects) are the two foundational light concepts at KS2. Co_teach_hints link C024 to C067 and C022 to C023.
Explain how light travels in straight lines and is reflected from surfaces
practice CuratedThe straight-line travel model explains both reflection (light bouncing off surfaces) and shadow formation; C067 is the explanatory model that underpins C023. Co_teach_hints link C023 and C067 directly.
Teaching Suggestions (1)
Study units and activities that deliver concepts in this domain.
Light and Shadows Investigation
Science Enquiry Fair TestPedagogical rationale
Fair testing the relationship between distance and shadow size produces a clear, quantitative pattern that pupils can graph and explain using the model of light travelling in straight lines. The investigation bridges practical measurement skills with the abstract idea of ray diagrams, building towards the Y6 requirement to explain how we see objects.
Access and Inclusion
1 of 4 concepts have identified access barriers.
Barrier types in this domain
Recommended support strategies
Prerequisites
Concepts from other domains that pupils should know before this domain.
Concepts (4)
Light and Vision
knowledge AI FacilitatedSC-KS2-C022
Understanding that light is needed to see — dark is the absence of light. In Year 3, this is the observable phenomenon; in Year 6, it is explained using the model that light travels in straight lines from sources to eyes or via reflection.
Teaching guidance
Create a dark den or use a blacked-out area to explore the concept that we need light to see. Demonstrate that in complete darkness we cannot see at all — dark is the absence of light, not a substance. Introduce the idea that we see objects because light from a source reaches our eyes — either directly from a light source (sun, lamp, candle) or after reflecting off objects. Discuss sun safety: never look directly at the sun. Compare objects that produce their own light (luminous — sun, torch, candle) with those that reflect light (non-luminous — moon, most objects).
Common misconceptions
The most common misconception is that we can see in complete darkness if we 'wait long enough for our eyes to adjust'. In complete darkness (no light at all), we cannot see anything. Children often believe the Moon produces its own light — it reflects sunlight. Some pupils think darkness is a substance that can be 'pushed away' by light, rather than understanding darkness as the absence of light.
Difficulty levels
Knowing that we need light to see things and that it is dark when there is no light.
Example task
Why can you not see in a completely dark room?
Model response: Because there is no light. We need light to see things.
Identifying sources of light (Sun, lamp, fire, torch) and understanding that we see objects because light from a source reaches our eyes, either directly or by bouncing off objects.
Example task
Name three light sources. How do we see a book in a lit room?
Model response: Light sources: the Sun, a lamp, a candle. We see the book because light from the lamp shines onto the book, bounces off the book's surface, and enters our eyes. Without the light reaching our eyes, we would not see the book.
Explaining how we see objects using the model that light travels from a source, reflects off objects and enters our eyes. Understanding that darkness is the absence of light.
Example task
Draw and label a diagram showing how we see a red apple when a lamp is on. Include the light source, the apple and the eye.
Model response: Diagram shows: lamp (light source) with arrows going to the apple, then arrows bouncing off the apple going to the eye. Labels: 'Light from the lamp travels to the apple', 'Light reflects off the apple's surface (red light reflects, other colours are absorbed)', 'Reflected light enters the eye, and we see a red apple'. In a dark room with no light source, no light reaches the apple or our eyes, so we see nothing.
Applying the light-and-vision model to explain everyday phenomena and recognising its development from Y3 observation to Y6 straight-line model.
Example task
Explain why you can see the Moon at night even though it is not a light source. Use the model of how we see things.
Model response: The Moon is not a light source — it does not produce its own light. We can see it because sunlight hits the Moon's surface and reflects off it. This reflected sunlight then travels through space to Earth and enters our eyes. We see the Moon the same way we see a book — by reflected light from a source. The light source is the Sun, even though the Sun is not visible to us at night (it is on the other side of Earth). This explains why the Moon's appearance changes through the month — we see different amounts of the sunlit side as the Moon orbits Earth.
Delivery rationale
Science observation concept — requires sustained observation of real phenomena with adult support.
Reflection of Light
knowledge AI DirectSC-KS2-C023
Understanding that light is reflected from surfaces, including mirrors and other reflective materials. In Year 3 this is observed; in Year 6 it is explained using the straight-line travel model.
Teaching guidance
Investigate reflection using mirrors, torches and darkened rooms. Show that shiny, smooth surfaces (mirrors, foil, still water) reflect light well, while rough or dark surfaces reflect less light. Use mirrors to redirect a torch beam around obstacles. Introduce the idea that we see most objects because light bounces off them into our eyes — even non-shiny objects reflect some light. Compare reflections in flat mirrors (clear image) with curved mirrors (distorted image). Connect to everyday applications: bicycle reflectors, reflective clothing, cat's eyes on roads.
Common misconceptions
Children often think that only shiny objects like mirrors reflect light. In fact, all visible objects reflect some light — that is how we see them. Some pupils believe that light only comes from very bright sources and do not recognise that a candle or even a glow-worm is a light source. Children may think reflection only occurs in mirrors, not understanding that water, polished floors and even walls reflect light.
Difficulty levels
Knowing that shiny surfaces like mirrors reflect light, demonstrated by seeing a torch beam bounce off a mirror.
Example task
Shine the torch at the mirror. What happens to the light?
Model response: The light bounces off the mirror and shines on the wall.
Understanding that light reflects off surfaces and that smooth, shiny surfaces reflect light best. We see most objects because light bounces off them into our eyes.
Example task
Why can you see your face in a mirror but not in a piece of carpet?
Model response: A mirror is very smooth and shiny, so it reflects light evenly — the light bounces off in a neat pattern that shows an image. Carpet is rough, so light bounces off in all different directions (scattered) and does not form a clear image. Both reflect some light — that is how we can see both of them — but only the mirror reflects it neatly enough to show a reflection.
Investigating reflection, identifying reflective and non-reflective surfaces, and understanding that the angle of reflection equals the angle at which light hits the surface.
Example task
We used a torch and mirror in a dark room. When we shone the torch at the mirror from the left, the light reflected to the right. What happens if we change the angle of the torch?
Model response: When we changed the angle of the torch, the reflected beam also changed direction. The angle of the reflected light matches the angle it arrives at. If the light hits the mirror straight on, it bounces straight back. If it hits at a steep angle, it reflects at the same steep angle on the other side. This is the law of reflection and it is why we can use mirrors to redirect light — for example, a periscope uses two mirrors to let you see over obstacles.
Applying reflection principles to explain everyday phenomena and design solutions using mirrors.
Example task
Design a periscope that lets you see over a wall. Explain how it works using your knowledge of reflection.
Model response: A periscope uses two mirrors placed at 45° angles inside a tube. Light from the scene above the wall enters the top, hits the first mirror at 45° and reflects downward through the tube. At the bottom, it hits the second mirror at 45° and reflects horizontally into the viewer's eyes. Because light travels in straight lines, the mirrors redirect the light path around the corner. Each mirror changes the direction by 90° — two 90° turns means the light effectively travels in a Z-shape from above the wall down to eye level. This is also how submarine periscopes work.
Delivery rationale
Science knowledge concept — factual content deliverable with visual representations and adaptive quizzing.
Shadow Formation
knowledge AI DirectSC-KS2-C024
Understanding that shadows are formed when light from a source is blocked by an opaque object. In Year 3, the pattern of shadow size changes is explored. In Year 6, shadow shape is explained using the straight-line travel model.
Teaching guidance
Investigate shadows using torches and opaque objects in a darkened area. Explore how shadow size changes with the distance between the light source and the object — closer to the light makes a larger shadow, closer to the screen makes a smaller shadow. Investigate how shadow shape relates to the shape of the object. Classify materials as opaque (blocks all light, creates shadow), translucent (lets some light through, creates faint shadow) or transparent (lets most light through, no shadow). In Year 6, revisit shadows and explain their sharp edges using the model that light travels in straight lines.
Common misconceptions
Children often think shadows have colour or are reflections of objects rather than areas where light has been blocked. Some pupils believe shadows are always the same size as the object, not understanding how distance from the light source affects shadow size. Children may think transparent objects have no effect on light at all, when in fact they can refract (bend) light passing through them.
Difficulty levels
Knowing that shadows form when something blocks the light, and that shadows are dark areas.
Example task
Stand in front of the lamp. What do you see on the wall behind you?
Model response: I can see my shadow on the wall. It is because my body is blocking the light.
Explaining that shadows form when opaque objects block light, and that transparent and translucent materials create different effects.
Example task
What happens when you put these three objects in front of the torch: cardboard, coloured glass, clear plastic?
Model response: Cardboard is opaque — it blocks all the light and makes a dark shadow. Coloured glass is translucent — it lets some light through but not clearly, making a faint coloured shadow. Clear plastic is transparent — it lets almost all the light through, so there is hardly any shadow.
Investigating how shadow size changes with the position of the light source or object, and explaining the results using the idea that light travels in straight lines.
Example task
We moved a toy figure closer to and further from a torch. What happened to the shadow? Explain why.
Model response: When the figure was close to the torch, the shadow on the wall was large. When the figure was far from the torch (closer to the wall), the shadow was smaller and sharper. This is because light travels in straight lines from the torch. When the object is close to the light, the light rays spread out more beyond the object, creating a larger shadow area. When the object is closer to the wall, the rays have less room to spread, making a smaller shadow. The shadow always has the same shape as the object because light cannot bend around it.
Using the straight-line model of light to explain shadow formation with ray diagrams, and applying this to real-world phenomena like sundials and eclipses.
Example task
Draw a ray diagram to explain why shadows change length during the day as the Sun moves across the sky. Why are shadows longest in the morning and evening?
Model response: Ray diagram showing the Sun low in the sky (morning): light rays hit a stick at a shallow angle, creating a long shadow stretching far from the base. Sun high in the sky (midday): rays come almost straight down, creating a short shadow directly below. Sun low again (evening): long shadow in the opposite direction from morning. Shadows are longest when the Sun is low because the light rays hit objects at a shallow angle, so the shadow stretches far along the ground. At midday, the rays are nearly vertical, so the shadow is shortest. This principle is how sundials tell the time — the shadow position changes predictably as the Sun moves across the sky. We must never look directly at the Sun when observing shadows.
Delivery rationale
Science knowledge concept — factual content deliverable with visual representations and adaptive quizzing.
Access barriers (3)
Understanding electrical circuits requires reasoning about invisible electron flow through wires. The circuit is visible but the electricity is not. Children with learning difficulties often develop misconceptions (electricity 'leaking out', current being 'used up') because the underlying process is abstract.
Building electrical circuits requires precise physical manipulation: connecting crocodile clips, inserting batteries correctly, handling small components. Children with fine motor difficulties may understand circuits conceptually but be unable to construct them independently.
Building a circuit follows a specific sequence: identify components, connect the battery, wire in the bulb/motor, close the circuit, test, modify. Each step must be completed correctly — one loose connection breaks the entire circuit.
Light Travels in Straight Lines
knowledge AI FacilitatedSC-KS2-C067
The explanatory model that light travels in straight lines from sources. This model explains why we see objects (light reaches our eyes directly from sources or via reflection), why shadows have the same shape as the object casting them, and how optical instruments work.
Teaching guidance
Demonstrate that light travels in straight lines by shining a torch through a series of cards with holes — the light only reaches the end if all holes are aligned. Use laser pointers (teacher-operated, safely) in a dusty or misty room to show the straight beam. Apply the straight-line model to explain how shadows have the same shape as the opaque object — draw ray diagrams showing light blocked by the object. Explain how we see objects: light from a source reflects off an object and travels in a straight line to our eyes. Use ray diagrams to model this process. Revisit shadow formation from Y3 and explain it using this model.
Common misconceptions
Children often think light travels from the eye to the object (emission theory) rather than from the object to the eye. This misconception has deep historical roots and is very persistent. Some pupils believe light can bend around corners — it cannot without a reflective or refractive surface. Children may think shadows are dark because they contain something (a dark substance) rather than understanding that a shadow is simply an area where light does not reach.
Difficulty levels
Knowing that light comes from light sources and travels to our eyes, allowing us to see things.
Example task
Shine a torch at the wall. Can you see the bright spot? Now put a book in front of the torch. What happens?
Model response: The bright spot disappears because the book blocks the light. The light cannot go through the book or around it. There is a shadow behind the book.
Understanding that light travels in straight lines and this explains why shadows have the same shape as the object blocking the light.
Example task
Line up three cards with small holes in the centre. Shine a torch through them. What happens if you move one card sideways?
Model response: When all three holes are lined up, the torch light passes through all of them because light travels in a straight line through each hole. When I move one card sideways, the light is blocked because the straight line from the torch no longer passes through all three holes. This proves light travels in straight lines — if it could curve, it would still get through.
Using the straight-line model of light to explain how we see objects (light reflects off them into our eyes), how shadows form, and drawing ray diagrams.
Example task
Draw a ray diagram to show how you see a book on a desk. Where does the light come from? Where does it go?
Model response: Ray diagram: Straight arrows from the light source (e.g., ceiling lamp) travel down to the book. The light reflects off the book's surface. Straight arrows from the book travel to my eyes. I see the book because light from the source has bounced off it and entered my eyes. I draw the rays as straight lines with arrows showing the direction: source → book → eye. If the light source were turned off, I would not see the book because no light would reach it to reflect. This model explains everything: we see luminous objects (sources like lamps, the Sun) because light travels directly from them to our eyes. We see non-luminous objects (books, walls, people) because light from a source reflects off them into our eyes.
Applying the straight-line model to explain complex phenomena like why shadows become larger/smaller and how mirrors redirect light.
Example task
In a darkened room, you hold a ball between a torch and a wall. As you move the ball closer to the torch, the shadow gets bigger. Draw a ray diagram to explain why.
Model response: Ray diagram: Draw the torch (point light source) on the left, the ball in the middle, and the wall (screen) on the right. Draw straight rays from the torch that just pass the top and bottom edges of the ball — these are the boundary rays. They continue in straight lines to the wall, where the gap between them defines the shadow size. Now move the ball closer to the torch: the boundary rays diverge at a wider angle because the ball intercepts a wider spread of light closer to the source. By the time these rays reach the wall, they are further apart — creating a larger shadow. Move the ball closer to the wall and the opposite happens — the boundary rays have less distance to spread, so the shadow is smaller and sharper. This is pure geometry — light travelling in straight lines from a point source creates a cone of shadow (umbra) that gets wider with distance. This is the same principle used in shadow puppetry and in optical instruments like cameras.
Delivery rationale
Science fair test concept — requires physical apparatus and variable control, but AI can structure the enquiry sequence.