Science and Technology K–6 · Years 1–2

Seeing sound: vibrations you can watch

Physical World, energy comes in different forms that can be detected (NSW 2017); Science understanding, Physical sciences (ACARA v9)

PracticalLow risk

The idea

Every sound comes from something vibrating, and the vibration can be made visible.

Safety card

Low riskAn adult supervises

Hazards

Water spills
Tuning fork tips near eyes
Balloons: latex is an allergy trigger, and the pieces of a burst balloon are a choking hazard for young children

Controls

Cup on a tray; fork held low
The class allergy register checked for latex before the lesson, and a latex-free balloon used where it names latex
The adult inflates, knots and holds the balloon against the speaker while learners feel it; no learner inflates, bites or stretches a balloon, and the adult collects every piece at once if one bursts

Note

No chemicals or heat. Record the activity on the school's risk assessment (Primary School RiskAssess, Ecosolve Australia, riskassess.com.au).

What you need

A drum or a bowl with cling film stretched tight; a teaspoon of uncooked rice
A 30 cm clear plastic ruler about 2 mm thick; a tuning fork, a rubber block and a cup of water; a balloon, latex-free where the class allergy register names latex; a speaker playing a low note at moderate volume

How to do it

Predict what you will see or feel when each thing makes a sound.
Sprinkle rice on the drum skin. Tap the skin beside the rice. Watch the rice. Tap harder.
Hold the ruler flat on the table edge with 20 cm hanging over. Twang the end. Watch it, then listen, and say whether you can see the vibration, hear it, or both. Shorten the overhang to 10 cm and twang again, and say the same thing.
Strike the tuning fork on the rubber block and dip the tips into the water.
The adult holds the blown-up balloon against the speaker; feel it with your fingertips.
Put your fingers on your throat and hum; then stop humming and feel again.

What you should see

The rice jumps when the skin is tapped and jumps higher for a harder tap. With 20 cm hanging over, the ruler is seen to blur but there is no note to hear, only a low clatter against the table: a plastic ruler vibrating over that length is at or below the 20 Hz the ear needs, and HyperPhysics gives the audible range as roughly 20 Hz to 20 kHz. Shortening the overhang to 10 cm makes it vibrate much faster, and now a clear low note is heard and the blur is harder to see, so this step is where the vibration is seen before it can be heard. The tuning fork splashes the water; the balloon buzzes against the fingers; the throat buzzes only while humming. The learner knows it worked when the rice stops jumping the moment the tapping stops, and when the 20 cm overhang can be seen vibrating without being heard.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Sound is made by the air, not by the object.
Loud sounds and soft sounds come from different things, not from the size of the vibration.
Anything that vibrates can be heard (a vibration slow enough is seen and felt but not heard).

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Science and Technology K-6 Syllabus (2017), NESA. Current syllabus; NESA's timeline is 2026 plan and prepare, 2027 start teaching the 2024 syllabus. Code read from the official syllabus document on 2026-09-22.ST1-8PW-S ST1-1WS-S
Science and Technology K-6 Syllabus (2024), NESA. Implementation from 2027, so this code describes the future syllabus. Code read from the outcomes page on 2026-09-22.ST1-SCI-01 ST1-PQU-01
Australian Curriculum v9AC9S2U02AC9S2I01AC9S2I02AC9S2I03AC9S2I06

Sources

The pages the author read to write this activity.

All Concept Studio activities