Science · Grade 4 · Energy in Motion: Waves and Information · Term 2

Light and Color

Investigating how white light is composed of different colors and how objects appear to have color.

• Ontario Curriculum Expectations
• 4-PS4-2

About This Topic

Light and color investigations reveal that white light from the sun contains all colors of the spectrum. Grade 4 students use prisms to separate white light into its rainbow components and explore why objects appear colored: they reflect certain wavelengths while absorbing others. For example, a red apple looks red under white light because it reflects red light to our eyes. This topic addresses key questions like explaining color perception, predicting color changes under colored lights, and designing separation experiments.

In the Energy in Motion unit, this content connects light waves to information transfer, such as how eyes detect color. Students develop skills in observation, prediction, and evidence-based explanations, aligning with standard 4-PS4-2 on generating patterns with light to model interactions.

Active learning shines here because students can directly manipulate prisms, filters, and flashlights to see color separation and selective reflection in real time. Building simple spectrometers or testing objects under gels turns predictions into visible results, fostering inquiry and retention through tangible exploration.

Key Questions

1. Explain why we see different colors.
2. Predict what would happen if an object that appears red was viewed under blue light.
3. Design an experiment to separate white light into its component colors.

Learning Objectives

• Identify the component colors within white light using a prism.
• Explain how an object's color is determined by the wavelengths of light it reflects and absorbs.
• Predict the perceived color of an object when illuminated by a light source of a different color.
• Design an investigation to demonstrate the separation of white light into its constituent colors.
• Analyze the relationship between light reflection, absorption, and perceived color.

Before You Start

Properties of Light

Why: Students need a basic understanding that light travels and can be observed before investigating its properties like color composition.

Basic Observation Skills

Why: Accurate observation is fundamental to identifying color changes and patterns when manipulating light sources and objects.

Key Vocabulary

spectrum	The range of all possible colors that make up white light, visible when light is separated by a prism.
wavelength	The distance between successive crests of a light wave, which determines its color.
reflection	The bouncing of light off a surface; the color we see is the light that is reflected.
absorption	The process by which an object takes in light energy, converting it into heat.
prism	A transparent object, usually glass or plastic, that refracts light and can separate white light into its component colors.

Watch Out for These Misconceptions

Common Misconception

Objects contain their color inside.

What to Teach Instead

Colors come from light wavelengths reflected off surfaces, not stored inside. Hands-on filter activities let students see the same object change color under different lights, challenging this idea through direct comparison and group discussion.

Common Misconception

Mixing all colors makes white light.

What to Teach Instead

White light splits into colors; mixing paints subtracts light differently. Prism experiments clarify this by showing white light as the source, with students rebuilding spectra to test mixing effects.

Common Misconception

Rainbows only appear after rain.

What to Teach Instead

Rainbows form anytime light refracts through water droplets. Outdoor observations or spray bottle demos with sunlight help students replicate conditions, linking refraction to prisms.

Active Learning Ideas

Prism Exploration: Rainbow Makers

Provide each pair with a prism, white light source, and white paper. Students direct light through the prism onto paper, rotate it to create a spectrum, and measure band widths. They sketch observations and note color order.

30 min·Pairs

Stations Rotation: Colored Filters

Set up stations with red, blue, green filters, flashlights, and colored objects. Groups shine filtered light on objects, predict appearances, then observe and record changes. Rotate every 10 minutes.

45 min·Small Groups

Design Challenge: Light Separator

In small groups, students design and test a device using household items like CDs or water glasses to split light. They present findings, explaining successes and adjustments.

50 min·Small Groups

Whole Class Demo: Shadow Colors

Project colored lights on a white screen with objects. Class predicts and discusses color shifts as lights change, voting on predictions before reveals.

20 min·Whole Class

Real-World Connections

• Lighting designers use their understanding of light and color to create specific moods and highlight features in theaters, museums, and retail spaces.
• Manufacturers of colored paints, fabrics, and inks carefully control the absorption and reflection properties of their materials to ensure consistent color appearance under various light sources.
• Forensic scientists analyze the spectral properties of evidence, such as fibers or paint chips, to identify their origin and composition.

Assessment Ideas

Quick Check

Provide students with a red object and a blue light source. Ask them to draw what they observe and write one sentence explaining why the object appears the color it does under the blue light.

Exit Ticket

On an exit ticket, ask students to list two component colors found in white light and explain in their own words why a green leaf appears green.

Discussion Prompt

Pose the question: 'Imagine you are designing a new traffic light system. How does understanding how we see color help you choose the best colors for stop, caution, and go signals?' Facilitate a brief class discussion.

Frequently Asked Questions

How do students explain why objects have color?

Students learn that white light carries all colors, but objects reflect only specific wavelengths while absorbing others. A green leaf reflects green light to our eyes. Experiments with flashlights and colored paper demonstrate this selective reflection, helping students articulate the process clearly.

What happens to a red object under blue light?

It appears black or very dark because the object absorbs blue light and reflects red, which blue light lacks. Prediction worksheets followed by filter tests confirm this, building students' ability to apply color theory to new scenarios.

How can active learning help with light and color?

Active approaches like prism stations and filter challenges make invisible light interactions visible and interactive. Students predict outcomes, test with peers, and revise ideas based on evidence, which deepens understanding and engagement far beyond lectures. Collaborative designs encourage experimentation skills central to the curriculum.

What experiments separate white light into colors?

Use prisms or diffraction gratings with sunlight or flashlights to refract light into spectra. Students shine light through, observe on screens, and trace rainbows. Variations with water-filled glasses reinforce refraction principles through repeated, guided trials.