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Science and Technology K–6 · Years 1–2

String telephone: sound travelling along a string

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

PracticalLow risk

The idea

Sound travels through solids as well as air, and a tight string carries a voice further than the air around it.

What you need

  • Two paper or plastic cups with a small hole in each base
  • 6 m of cotton string threaded through both holes and knotted inside each cup; a tape measure
  • A quiet outdoor space or corridor

How to do it

  1. Predict whether a whisper will be easier to hear through the tight string or through the open air.
  2. Step apart until the string is tight and measure the distance between the two people. One whispers into a cup while the other holds the cup to an ear. Swap.
  3. Let the string go slack and whisper again.
  4. Have a third person pinch the tight string in the middle while whispering continues.
  5. Whisper the same words across the same distance of open air with no cups and compare.

What you should see

With the string tight the whisper is heard clearly; across the open air the same whisper is fainter or lost; with the string slack or pinched the sound stops or fades, because the vibration is no longer carried along the string. The learner knows it worked when the listener repeats the whispered words correctly through the tight string and the slack or pinched string cuts the sound.

What changes

What you change
state of the string (tight, slack, pinched)
What you measure
whether the whisper is heard and repeated correctly
What you keep the same
  • same distance (measured when the string is tight)
  • same whisper volume
  • same cups

Common misconceptions

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

  • Sound only travels through air.
  • The cups make the sound louder by themselves.

Safety card

Low riskLearners carry it out

Hazards

  • String across a walkway

Controls

  • Used away from doorways

Note

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

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-SST1-1WS-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-01ST1-PQU-01
  • Australian Curriculum v9AC9S2U02AC9S2I01AC9S2I02AC9S2I05

Sources

The pages the author read to write this activity.

  1. www.scootle.edu.au/ec/search?accContentId=AC9S2U02
  2. www.nsw.gov.au/education-and-training/nesa/curriculum/science/science-and-technology-k-6-2017
  3. primaryconnections.org.au/teaching-sequences/year-2/sound-studio

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