Science · 2nd Grade · The Inventor's Workshop · Weeks 28-36

Energy: Light and Sound

Students will investigate different forms of energy, focusing on light and sound, and how they travel and interact with objects.

• Common Core State Standards
• 1-PS4-1
• 1-PS4-2
• 1-PS4-3

About This Topic

Light and sound are two of the most pervasive forms of energy in students' daily lives, and this topic gives second graders a systematic framework for investigating how each one travels and interacts with objects. Aligned with NGSS 1-PS4-1, 1-PS4-2, and 1-PS4-3, the topic revisits concepts students first encountered in first grade with greater attention to evidence, prediction, and the relationship between a material's properties and how it interacts with light and sound.

Students investigate how light travels in straight lines from a source and why we see objects when reflected light reaches our eyes. They compare multiple light sources such as sunlight, flashlights, and glowing screens, and they test how changing the material a sound travels through affects what is heard. These investigations build toward the understanding that energy behavior depends on the properties of the materials it encounters.

Active learning is central to both investigations because light and sound phenomena are invisible or fleeting, and students need direct hands-on experiments to form accurate mental models. When students block, reflect, and redirect light themselves, or feel vibrations in surfaces while producing sound, they gather physical evidence that descriptions or diagrams cannot replicate.

Key Questions

1. Explain how light travels and how we see objects.
2. Differentiate between various sources of light and sound.
3. Predict how sound will change when it travels through different materials.

Learning Objectives

• Compare and contrast at least three different sources of light based on their properties.
• Explain how light travels in straight lines and reflects off objects to allow us to see.
• Predict how sound will change when it travels through different materials, such as solid, liquid, and gas.
• Identify the source of vibrations that produce sound in common objects.

Before You Start

Properties of Objects

Why: Students need to be familiar with describing and sorting objects based on their observable properties to compare light and sound interactions.

Basic Needs of Living Things

Why: Understanding that light is necessary for plants to grow provides a foundational connection to light as a form of energy.

Key Vocabulary

light source	An object that produces its own light, like the sun or a lamp.
reflection	When light bounces off a surface, like a mirror or a wall, allowing us to see objects.
vibration	A rapid back-and-forth movement that produces sound, like when a drum is hit.
sound travel	How sound waves move through different materials, like air, water, or solids.

Watch Out for These Misconceptions

Common Misconception

Students often believe that their eyes send out beams of light to see objects.

What to Teach Instead

We see objects because light travels from a source, reflects off the object, and then enters our eyes. This is deeply counterintuitive for young students. Having students sit in a darkened space and observe that an object becomes invisible the moment the light source is blocked gives direct evidence that the object never produced its own light and that seeing depends entirely on reflected light reaching the eye.

Common Misconception

Children frequently think sound travels the same way through any material, or that it does not need a medium at all.

What to Teach Instead

Sound requires a medium (solid, liquid, or gas) and travels at different speeds through each. Comparing how clearly a tap sounds through open air versus through a table surface with one ear pressed against it gives students direct, physical evidence that the material matters. Active listening tasks make this difference far more convincing than any verbal explanation.

Common Misconception

Students sometimes confuse loudness and pitch, assuming a louder sound is always a higher-pitched one.

What to Teach Instead

Loudness and pitch are independent properties of sound. A drum can produce a loud, low-pitched sound while a whistle produces a softer, high-pitched one. Having students change only one variable at a time, such as plucking a string softly versus hard (loudness changes) and then comparing a short string to a long one (pitch changes), lets them experience each property separately and avoid conflating them.

Active Learning Ideas

Inquiry Circle: The Shadow Lab

Pairs shine a flashlight at a white screen and hold different materials in the beam: opaque cardstock, translucent tissue paper, and a clear plastic sheet. Students predict whether each material will create a sharp shadow, a dim shadow, or no shadow, then test and record observations. After all tests, groups sort the materials into three categories and connect the result to the idea that light travels in straight lines.

35 min·Pairs

Simulation Game: Vibration Detectives

Students press their fingertips lightly against their throat while humming, then against a ruler twanged on the desk edge, then against the desk surface while a partner taps the other end. Students record what they feel at each location and connect the vibration sensation to the sound they hear. A whole-class debrief establishes that all sound comes from something that is moving.

20 min·Whole Class

Think-Pair-Share: Sources of Light and Reflection

Display two groups of objects: one labeled 'makes its own light' (sun, flashlight, candle, screen) and one unlabeled set visible only because they reflect light (moon, a book, a student's shirt). Students sort the second set with a partner and discuss what the difference reveals about how we see objects. This builds the distinction between light-producing and light-reflecting objects without requiring formal vocabulary.

20 min·Pairs

Gallery Walk: Sound Through Different Materials

Set up four stations: tapping on a table surface heard through the air, tapping with an ear pressed to the table, whispering through a cardboard tube, and tapping beside a cup of water while touching the rim. Students visit each station, record what they hear, and rank the four from loudest to softest. Groups compare rankings and discuss which material carried the sound most effectively and why.

30 min·Small Groups

Real-World Connections

• Stage lighting designers use their understanding of how light travels and reflects to create specific moods and illuminate performers on a theater stage.
• Acoustic engineers design concert halls and recording studios by considering how sound travels through different materials to ensure clear audio and minimize echoes.

Assessment Ideas

Exit Ticket

Provide students with a picture of a flashlight and a picture of the moon. Ask them to write one sentence explaining which is a light source and why. Then, ask them to draw a line showing how light travels from the flashlight to an object.

Quick Check

Hold up a tuning fork and strike it. Ask students to describe what they hear and feel. Then, ask them to explain what is causing the sound and how it is traveling to their ears.

Discussion Prompt

Ask students: 'Imagine you are trying to hear a friend whisper across a room. What materials are between you? How might those materials change the sound you hear?' Encourage them to share predictions and reasons.

Frequently Asked Questions

What NGSS standards does light and sound energy address in 2nd grade?

This topic primarily addresses 1-PS4-1 (investigating how sound is produced and how vibrating objects make sound), 1-PS4-2 (understanding that objects can be seen only when illuminated), and 1-PS4-3 (testing how different materials interact with a beam of light). These standards were introduced in first grade; second grade is an opportunity to deepen investigation quality, increase evidence rigor, and build stronger connections between material properties and energy behavior.

How do you explain how we see objects to 2nd graders?

Start with a dark box or a dimmed room. Ask students whether they can see an object when there is no light source, and establish that they cannot. Then introduce the idea that light must travel from a source, hit the object, and reflect into our eyes for us to see it. The moon is a useful real-world example: it appears bright, but only because it reflects sunlight. Our eyes receive that reflected light, which is why we can see it at night.

How does active learning help students understand light and sound energy?

Both light and sound are phenomena students experience constantly but rarely examine closely. Hands-on investigations, like blocking a light beam to observe shadow formation or pressing ears against surfaces to compare sound transmission, make invisible processes observable and testable. When students gather their own evidence through prediction and experiment, they build mental models far more durable than those formed by watching demonstrations, and they practice the evidence-based reasoning central to NGSS science practice.

How does sound travel differently through solids, liquids, and gases?

Sound travels fastest through solids, slower through liquids, and slowest through gases like air. Particles in solids are more tightly packed and pass vibrations more efficiently. Students notice this directly when they press an ear to a table and hear a tap more clearly than when listening through the air. This also explains why pressing an ear against a wall lets you hear sounds from an adjacent room more clearly than listening through the open air between rooms.