Sound Waves

Overview

In this lesson, students investigate how sound travels and how changing a source or medium affects what we hear. They use structured observations to answer “what happens if…” questions, building an evidence-based explanation of waves.

Learning intentions

Students will:

• recognise that sound is made when something vibrates
• describe that sound travels through a medium and cannot travel through a vacuum
• investigate how changing the distance and strength of a sound source changes what they hear
• use observations to answer challenge questions about sound waves and how they behave

Success criteria

Students can:

• explain that vibrating objects produce sound
• say that sound needs a medium (e.g., air, water, solids) to travel
• predict whether sound will be heard in different situations (including “vacuum”)
• justify answers using at least one observation from their investigation

Curriculum links

• Light is also part of the Year 3 “Light” strand, but this lesson focuses on sound waves (waves in general) to meet your request for a waves lesson.
• Students use scientific enquiry: observe, record, compare, and draw conclusions from evidence.
• Students communicate findings clearly, using correct scientific vocabulary (vibrate, medium, travel).

Lesson structure (30 minutes)

1. 0–5 min · Hook question. Teacher demonstrates a vibrating object (e.g., a buzzer or ruler plucked on the desk) and asks: “What do you notice about the object?” Students write one sentence: “Sound happens when…”.

2. 5–12 min · Mini teach: sound as a wave. Teacher explains that sound is produced by vibrations and travels as a wave through a medium; emphasise “vacuum = no sound.” Students complete a quick “True/False + reason” on their sheet (e.g., “Sound can travel through space”): they must give a reason.

3. 12–20 min · Investigation: distance and volume. Teacher sets up two stations: (a) a sound source (phone/tuning fork/buzzer) and (b) students’ ears measured at distances (e.g., 0 cm, 50 cm, 100 cm). Students take short observations: “How loud does it seem?” and “Do you hear it clearly?” They record one graph-style line (distance vs perceived loudness using a 1–5 scale).

4. 20–26 min · Challenge: medium and prediction. Teacher introduces a medium challenge set: “Which of these would sound travel through—air, water, solid?” plus a “vacuum” scenario. Students answer in pairs: choose, predict, and then give a justification using the rule “sound needs a medium.”

5. 26–30 min · Answer checking and exit ticket. Teacher hands out the teacher answer sheet briefly to self-check (students mark only their own). Students finish an exit ticket: one prediction question and one “explain with evidence” question.

Resources

• Sound source for students to use (tuning fork or buzzer with a consistent setting)
• Measuring tape or marked ruler for distance trials
• Timer (phone) and a quiet space
• Recording sheet (distance vs perceived loudness, 1–5 scale)
• True/False question sheet
• Challenge question sheet (medium/vacuum)
• Teacher answer sheet (for final self-check)
• Optional: balloon-in-a-box or “sealed container” demonstration if available (teacher-led)

Assessment

• Check 1 (during Hook): review students’ sentence about vibrating objects producing sound.
• Check 2 (during investigation): look for correct use of distance changes and whether they record evidence consistently.
• Exit ticket: one prediction about whether sound travels in each scenario and one explanation sentence referencing “vibrate” and “medium”.

Differentiation

• Support: sentence starters on the worksheets (e.g., “Sound is made when…”, “Sound travels through…”, “It cannot travel through…”).
• Support: provide a vocabulary word bank with “vibrate / medium / travel / vacuum / loud / quiet”.
• Challenge (for higher confidence): ask students to rank three situations by expected loudness and justify using their distance results plus the medium rule.
• EAL/SEN: allow oral rehearsal before writing; accept diagrams (e.g., wave lines) as part of explanations.

Answer sheet (teacher use)

Part A: True/False with reason

1. Sound can be made by vibrating objects.

• True — vibrating object produces sound.

2. Sound can travel through a vacuum.

• False — sound needs a medium to travel.

3. If you move farther from a sound source, it will usually sound quieter.

• True — the wave spreads out and is harder to detect clearly.

4. Sound travels through solids, liquids and gases (not just air).

• True — sound can travel through different media.

Part B: Investigation recording (distance vs perceived loudness)

Example expected trend (students may vary slightly):

• 0 cm → 5 (very loud/clear)
• 50 cm → 3–4 (still audible, less clear)
• 100 cm → 1–2 (quiet/less clear or harder to hear)

Correct reasoning to look for:

• “As distance increases, the sound becomes quieter/less clear.”
• Students mention sound “travels” from the source to the listener through the medium (air).

Part C: Challenge questions (medium and vacuum)

1. Would sound be heard in air?

• Yes — air is a medium.

2. Would sound be heard underwater?

• Yes — water is a medium.

3. Would sound be heard through a solid (e.g., touching a desk while a buzzer vibrates)?

• Yes — solids can carry sound.

4. Would sound be heard in space/vacuum?

• No — no medium, so sound cannot travel.

Exit ticket expected answers

• Prediction: “Sound will be heard in air but not in a vacuum.”
• Explanation: must include both ideas: vibrating object makes sound, and sound travels only through a medium.

(If you want, tell me what equipment you have—tuning forks, buzzers, balloon demo, etc.—and I’ll tailor the sheets to match.)