Science · Year 3 · Pushing and Pulling · Term 4

Light: Sources and Shadows

Students will investigate natural and artificial light sources and how light travels in straight lines to form shadows.

• ACARA Content Descriptions
• AC9S3U03

About This Topic

Light sources and shadows help Year 3 students explore how light behaves in everyday settings. They identify natural sources, such as the sun, and artificial ones, like flashlights and lamps. Students learn that light travels in straight lines from these sources. When objects block the light path, shadows form. This content matches AC9S3U03 and connects to observations of daily shadows from trees or buildings.

Students compare light from the distant sun, which sends nearly parallel rays and creates sharp midday shadows, to light from a nearby flashlight, which spreads out and produces larger, fuzzier shadows. They analyze why shadows change size and shape by moving objects closer or farther from the source or screen. Designing experiments to test these variables builds skills in prediction, observation, and fair testing.

Active learning shines here because students can manipulate flashlights, objects, and screens in darkened spaces to see effects instantly. Tracing shadows outdoors or creating shadow art in pairs turns theory into play. These methods make concepts visible, spark curiosity, and support peer discussions that refine understanding.

Key Questions

1. Analyze why shadows are formed when an object blocks light.
2. Compare the light produced by the sun to the light from a flashlight.
3. Design an experiment to change the size and shape of a shadow.

Learning Objectives

• Identify natural and artificial light sources in a given environment.
• Explain how light travels in straight lines to form shadows.
• Compare the characteristics of shadows cast by different objects and light sources.
• Design an investigation to observe how changing the distance between an object and a light source affects shadow size.
• Analyze why shadows change shape when an object is moved or rotated.

Before You Start

Properties of Objects

Why: Students need to understand that objects have different properties, such as transparency and opacity, which are essential for understanding shadow formation.

Basic Measurement

Why: Students will benefit from prior experience with measuring length to compare the sizes of different shadows.

Key Vocabulary

Light Source	Anything that produces light. This can be natural, like the sun, or artificial, like a lamp.
Shadow	A dark area formed when an opaque object blocks light. Shadows are formed because light travels in straight lines.
Opaque	An object that does not allow light to pass through it. Opaque objects cast shadows.
Light Ray	A straight line representing the path that light travels from a source.

Watch Out for These Misconceptions

Common Misconception

Shadows are the same size as the object.

What to Teach Instead

Shadows enlarge or shrink based on light source and object distances. Hands-on tests with rulers and flashlights let students measure differences firsthand. Pair discussions reveal how diverging light rays spread out, correcting size misconceptions through evidence.

Common Misconception

Light curves around objects to make shadows.

What to Teach Instead

Light travels only in straight lines and stops at opaque objects. Shadow puppet activities show clear edges where light is blocked. Group experiments comparing blocked and unblocked paths build accurate mental models via direct observation.

Common Misconception

All light sources produce identical shadows.

What to Teach Instead

Shadows differ by source distance and type, like sun versus flashlight. Outdoor hunts paired with indoor simulations highlight these contrasts. Collaborative charting helps students spot patterns and discard uniform light ideas.

Active Learning Ideas

Stations Rotation: Shadow Makers

Prepare four stations with flashlights, objects of different sizes, and white screens. At each station, students predict and test how moving the light or object changes shadow size. Groups rotate every 10 minutes, sketch results, and share findings. Conclude with a class chart of patterns.

45 min·Small Groups

Pairs Experiment: Light Distance Test

Partners use a flashlight, toy, and wall to measure shadow lengths at three distances. They record data in a table, then switch roles to test object distance. Discuss which change has a bigger effect on shadow size.

30 min·Pairs

Whole Class: Outdoor Shadow Hunt

Students mark positions with chalk to trace their shadows at different times. Pairs measure and compare lengths, noting sun position changes. Back inside, they draw graphs and explain patterns using straight-line light travel.

50 min·Whole Class

Individual: Shadow Shape Designer

Each student uses a flashlight and cut-out shapes to project shadows on paper. They bend or twist shapes and draw the results. Share one creative shadow and describe the light-object setup.

20 min·Individual

Real-World Connections

• Stage lighting designers use their understanding of light and shadows to create specific moods and effects for theatrical productions, controlling the size and sharpness of shadows cast by actors and props.
• Architects and urban planners consider how buildings and trees cast shadows to optimize sunlight in public spaces and residential areas, influencing comfort and energy use.
• Photographers manipulate light sources and subjects to control shadow depth and shape, which is crucial for portraiture and landscape photography to achieve desired artistic outcomes.

Assessment Ideas

Quick Check

Provide students with a flashlight, a small toy, and a blank wall in a darkened room. Ask them to demonstrate how to make the shadow larger and then how to make it smaller. Observe their actions and ask them to explain what they did and why it worked.

Exit Ticket

On a slip of paper, have students draw a simple diagram showing a light source, an object, and a shadow. Ask them to label each part and write one sentence explaining why the shadow was formed.

Discussion Prompt

Pose the question: 'Imagine you are walking outside on a sunny day. Why does the shadow of a tall tree look different in the morning compared to the afternoon?' Facilitate a class discussion, guiding students to connect the sun's position to the shadow's shape and length.

Frequently Asked Questions

How do I teach Year 3 students that light travels in straight lines?

Use flashlights in a dark room to shine light through cardboard slits or around corners. Students observe straight paths on screens and note blocking by objects. Follow with shadow predictions: if light bent, no shadows would form. This simple setup, lasting 20 minutes, confirms the concept through visible rays and peer predictions.

What activities explore shadow size and shape changes?

Set up flashlight stations where students adjust distances to see shadows grow or shrink. Outdoor shadow tracing at intervals shows time-based changes from sun movement. Pairs design experiments varying object height or screen distance, recording with sketches and measurements. These build fair testing skills aligned to AC9S3U03.

How can active learning benefit light and shadows lessons?

Active methods like manipulating flashlights and tracing shadows give instant feedback on light's straight travel. Students in pairs or groups predict, test, and discuss changes, deepening understanding beyond diagrams. Shadow plays or hunts boost engagement, retention, and skills like observation and collaboration, making abstract science tangible and fun.

What are common misconceptions about light sources?

Students may think the sun works like a flashlight or that artificial lights are weaker. Compare midday sharp shadows to flashlight's large ones via side-by-side photos or demos. Experiments measuring light intensity with shadow crispness clarify differences. Class talks refine ideas, linking to natural and artificial source properties.