Light and Shadows Investigation

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Enquiry questions

How are shadows formed, and what affects their size?

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Concepts

This study delivers 1 primary concept and 3 secondary concepts.

Primary concept: Light and Vision (SC-KS2-C022)

Type: Knowledge | Teaching weight: 3/6

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). Key vocabulary: light, dark, light source, luminous, reflect, shadow, see, eye, torch, candle, sun, absence, visible, darkness, bright, dim 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.

Differentiation

Model response (Entry): Because there is no light. We need light to see things.

Model response (Developing): 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.

Model response (Expected): 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.

Model response (Greater Depth): 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.

Secondary concept: Reflection of Light (SC-KS2-C023)

Type: Knowledge | Teaching weight: 3/6

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.

Differentiation

Secondary concept: Shadow Formation (SC-KS2-C024)

Type: Knowledge | Teaching weight: 3/6

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.

Differentiation

Secondary concept: Light Travels in Straight Lines (SC-KS2-C067)

Type: Knowledge | Teaching weight: 5/6

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.

Differentiation

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Thinking lens: Cause and Effect (primary)

Key question: What caused this to happen, and how do we know? Why this lens fits: Fair testing and investigations are designed to isolate variables and establish causal relationships — the cognitive demand is reasoning from controlled evidence to causal claims. Question stems for KS2:

What caused this to happen?

How could we check if that is the reason?

Is there more than one reason?

What would happen if we changed just one thing?

Secondary lens: Patterns — Data from repeated investigations reveals patterns that allow pupils to generalise their findings beyond the specific test conditions.

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Session structure: Fair Test

Fair Test

The classic scientific enquiry: formulating a testable question, making a prediction based on scientific understanding, designing a method that controls variables, collecting and recording data systematically, analysing results, and drawing a conclusion linked back to the original hypothesis.

question → hypothesis → method → data_collection → analysis → conclusion Assessment: Structured scientific report including question, hypothesis with reasoning, method with variables identified, results table/graph, and conclusion evaluating whether results support the hypothesis. Teacher note: Use the FAIR TEST template: frame a testable question and guide pupils to identify the variable they will change, measure, and keep the same. Support them in making a prediction with a scientific reason. Collect measurements using appropriate equipment and record results in a table. Guide pupils to describe patterns in their results and say whether their prediction was supported. KS2 question stems:

What is our testable question?

What will you change, measure, and keep the same?

What pattern can you see in your results?

Does the evidence support your prediction? How do you know?

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Variables

Independent: distance between light source and object Dependent: size of shadow (cm height) Controlled: same light source, same object, same screen distance, darkened room

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Equipment and safety

Equipment:

torches

opaque objects

white screen/card

mirrors

ruler

metre stick

Safety notes: Do not shine torches directly into eyes. Supervise mirror use — reflected light can dazzle. Darken the room for best results but ensure safe movement. (Hazard level: low)

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Expected outcome

Shadows form when opaque objects block light. Shadow size increases as the object moves closer to the light source. Light travels in straight lines. We see objects because light reflects off them into our eyes.

Recording format: results table, line graph, ray diagram showing light travel

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Enquiry type

Fair Test

A controlled investigation where one variable is deliberately changed while all others are kept the same, to determine whether the changed variable has an effect on a measured outcome. The gold-standard enquiry type for causal questions in science.

KS2 guidance: At KS2, fair tests should involve tangible, observable variables. Pupils identify what they will change, measure, and keep the same. Predictions use 'I think... because...' stems. Data is recorded in tables and presented as bar charts or line graphs. Conclusions state whether the prediction was supported and give a simple causal explanation. Question stems:

How does [independent variable] affect [dependent variable]?

Does changing [variable] make a difference to [outcome]?

What is the relationship between [variable A] and [variable B]?

Teacher scaffold:

What will you change? (independent variable)

What will you measure or observe? (dependent variable)

What will you keep the same? (controlled variables)

What do you predict will happen? Why?

Was your prediction correct? What does the evidence show?

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Known misconceptions

Shadows have colour

What pupils may say: Shadows have colour — a red object makes a red shadow. Correct explanation: A shadow is an area where light has been blocked by an opaque object. Shadows are dark (absence of light), not coloured. The colour of the object does not affect the colour of its shadow. The shadow takes the shape of the object because light travels in straight lines. Diagnostic questions:

What colour is the shadow of a red ball? Why?

What actually IS a shadow?

Can you make a coloured shadow? (Only with coloured lights, not coloured objects.)

Eyes emit light

What pupils may say: Our eyes send out light beams to see things. Correct explanation: We see objects because light from a source (the sun, a lamp, etc.) reflects off objects and enters our eyes. Our eyes are detectors, not emitters. The ancient Greek 'emission theory' of vision has been disproved — nothing comes out of our eyes. In a completely dark room, we cannot see anything because there is no light to reflect. Diagnostic questions:

If our eyes sent out light, would we be able to see in a completely dark room?

Draw an arrow diagram showing how you see a book on a table.

What is the role of light in how we see things?

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Why this study matters

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.

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Pitfalls to avoid

Pupils think their eyes send out light to see objects — reinforce that we see because light reflects off objects into our eyes

Difficulty understanding that the shadow is not 'attached' to the object — use a torch and move both object and screen

Assuming coloured filters make coloured shadows — the shadow is where light is blocked, not where colour appears

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Working scientifically skills (KS2)

These disciplinary skills should be woven through teaching, not taught in isolation:

Identifying and classifying — Sorting and grouping objects, organisms or materials according to their observable characteristics, recognising that things can be classified in more than one way depending on which features are selected.

Making and recording observations with evaluation of method — Conducting observations and measurements using a range of apparatus and methods appropriate to the investigation, and critically evaluating the reliability of those methods with reasoned suggestions for improvement.

Communicating findings — Presenting the outcomes of scientific enquiry in oral and written forms — including explanations, displays and presentations — using appropriate scientific language and representations to convey methods, results and conclusions clearly to others.

Asking relevant questions and selecting enquiry types — Formulating focused scientific questions and selecting the most appropriate enquiry method to answer them, choosing between observing over time, pattern seeking, classifying, comparative tests, fair tests, or secondary research as the situation demands.

Evaluating evidence and understanding scientific knowledge development — Critically evaluating data for random and systematic error, and understanding how scientific methods and theories evolve as new evidence emerges — including the roles of publication, peer review and replication in establishing trustworthy scientific knowledge.

Drawing conclusions and evaluating evidence — Using collected data to draw conclusions, identify causal relationships, make and test predictions, and assess the degree of trust that can be placed in results, recognising when evidence supports or refutes a scientific idea.

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Vocabulary word mat

Prior knowledge (retrieval plan)

Pupils should already know the following from earlier units:

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Scaffolding and inclusion (Y3)

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Knowledge organiser

Key terms:

light source

opaque

transparent

translucent

shadow

reflection

ray

straight line

Core facts (expected standard):

Light and Vision: 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.

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Graph context

Node type: ScienceEnquiry | Study ID: SE-KS2-007 Concept IDs:

SC-KS2-C022: Light and Vision (primary)

SC-KS2-C023: Reflection of Light

SC-KS2-C024: Shadow Formation

SC-KS2-C067: Light Travels in Straight Lines

Cypher query:

``cypher

MATCH (ts:ScienceEnquiry {enquiry_id: 'SE-KS2-007'})

-[:DELIVERS_VIA]->(c:Concept)

-[:HAS_DIFFICULTY_LEVEL]->(dl)

RETURN c.name, dl.label, dl.description

``

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Generated from the UK Curriculum Knowledge Graph — zero LLM generation.