Science · Year 5 · Light and Sound · Summer Term

Shadows and Light Blocking

Understanding how shadows are formed when opaque objects block light, and how shadow size and shape can change.

• National Curriculum Attainment Targets
• NC-KS2-Science-Y5-Light-2

About This Topic

Shadows form when an opaque object blocks light rays that travel in straight lines from a source, creating a dark patch on a surface behind the object. In Year 5, students observe that shadow size increases as the object moves farther from the light source or closer to the screen, while shape changes with the angle of light. These patterns follow from light's straight path and help explain everyday sights like tree shadows at sunset.

This topic fits the Light and Sound unit by combining observation, prediction, and creative tasks like puppet shows. Students conduct fair tests, varying one factor such as light position while keeping others constant, which strengthens experimental skills required by the National Curriculum. Links to mathematics arise in measuring shadow lengths.

Active learning suits this topic perfectly. With torches, rulers, and simple objects, students test predictions immediately and adjust setups based on results. Small group rotations build collaboration, while recording data makes patterns clear and turns inquiry into lasting understanding.

Key Questions

1. Explain how shadows are formed and why they change shape and size.
2. Predict how the position of a light source will affect the shadow cast by an object.
3. Design a puppet show using shadows to tell a story.

Learning Objectives

• Explain the formation of shadows by identifying the roles of light sources, opaque objects, and surfaces.
• Predict how changes in the distance between an object and a light source, or an object and a surface, will alter shadow size.
• Analyze how the angle of a light source affects the shape and orientation of a shadow.
• Design a simple shadow puppet to cast a specific shape or form.
• Critique the effectiveness of different shadow puppet designs in conveying a story element.

Before You Start

Properties of Light

Why: Students need to know that light travels in straight lines to understand how opaque objects block it and form shadows.

Materials and their Properties

Why: Understanding that some materials are transparent, translucent, or opaque is fundamental to explaining why shadows are formed by certain objects.

Key Vocabulary

Opaque	An object that does not allow light to pass through it, causing a shadow to form behind it.
Light Source	Anything that emits light, such as the sun or a lamp, which travels in straight lines.
Shadow	A dark area formed when an opaque object blocks light from a source.
Projection	The act of casting a shadow onto a surface, where the shape and size depend on the object's position relative to the light and surface.

Watch Out for These Misconceptions

Common Misconception

Shadows are always the same size as the object.

What to Teach Instead

Shadow size depends on distances between light, object, and screen. Measuring activities reveal longer shadows when objects move away from light, helping students revise ideas through evidence. Group predictions followed by tests build accurate models.

Common Misconception

Light bends around objects to make shadows fuzzy.

What to Teach Instead

Light travels straight, so fuzziness comes from light source size, not bending. Torch experiments show sharp shadows with distant point sources, clearer in discussions where students trace rays on paper.

Common Misconception

Shadows only form from the sun.

What to Teach Instead

Any light source works if strong enough. Classroom torch setups prove this instantly, with students comparing sun and artificial shadows to generalize the blocking principle.

Active Learning Ideas

Fair Test: Shadow Lengths

Provide torches, metre sticks, teddy bears, and paper screens. Students fix the screen distance and move the object between torch and screen, measuring shadow lengths at three positions. They record in tables and graph results to spot the pattern. Pairs discuss why lengths change.

35 min·Pairs

Stations Rotation: Light Angles

Set up three stations with torches at high, low, and side angles casting shadows from a fixed object. Groups spend 10 minutes at each, sketching shadows and predicting the next station's outcome. Whole class shares sketches to compare.

40 min·Small Groups

Design Challenge: Shadow Puppets

Students cut animal shapes from card, attach to sticks, and create a 2-minute story show behind a sheet with a torch. Practice predicts shadow effects from light position. Perform for class with peer feedback on clarity.

50 min·Small Groups

Outdoor Prediction: Sun Shadows

Place sticks in ground at schoolyard spots. Pairs mark initial shadows, predict positions hourly using compass and sun path knowledge, then measure actuals. Compare predictions in plenary.

30 min·Pairs

Real-World Connections

• Stage lighting designers use their understanding of light and shadow to create atmosphere and focus attention in theatre productions, controlling the size, shape, and movement of shadows cast by actors and props.
• Astronomers study the shadows cast by celestial bodies, such as lunar and solar eclipses, to understand their movements and properties, using shadow measurements to calculate distances and sizes.
• Animators creating stop-motion or silhouette animations rely on precise control of light sources and object placement to generate specific shadow effects that tell a visual story.

Assessment Ideas

Exit Ticket

Provide students with a diagram showing a light source, an opaque object, and a screen. Ask them to draw the resulting shadow and write one sentence explaining why it formed. Then, ask them to predict what would happen to the shadow if the object were moved closer to the light source.

Quick Check

During a hands-on activity, circulate with a checklist. Observe students as they manipulate objects and light sources. Ask targeted questions like: 'What happens to the shadow when you move the torch further away? Why?' or 'How could you make the shadow longer?'

Discussion Prompt

Pose the question: 'Imagine you are designing a shadow puppet show for younger children. What kind of object would you use to create a clear shadow of a dog? How would you move the light source to make the dog appear to bark or wag its tail?' Facilitate a brief class discussion where students share their ideas.

Frequently Asked Questions

How can active learning help Year 5 students understand shadows?

Active approaches like manipulating torches and objects give instant feedback on predictions, making straight-line travel visible. Small group stations encourage talk to challenge ideas, while designs like puppet shows apply concepts creatively. Data recording reveals patterns, turning observations into explanations that stick beyond worksheets.

What everyday examples explain shadow changes?

Point to long afternoon shadows from buildings or short midday ones from people. Hands-on torch models replicate these, letting students measure and predict. This connects school learning to real life, boosting engagement and retention of size factors.

What materials are needed for shadow experiments?

Basic items include torches, opaque toys or cutouts, metre sticks, white sheets or walls as screens, and notebooks for data. Add compasses for sun work. These low-cost setups support fair tests on distance and angle, scalable for whole classes.

How to assess shadow and light blocking understanding?

Use prediction sketches before activities, then compare to results. Peer reviews of puppet shows check application. End with explanations like 'draw rays to show why shadows lengthen.' Rubrics score observation accuracy and variable control.