Sound Wave
Light, Sound and Waves

Talking telephones

Classroom Activity for 5-11 Supporting Physics Teaching

What the Activity is for

Vibrations travel from source to detector, along with string.

Sending messages using sound enables us to think about the vibrations. This activity, as well as enabling an engaging and exciting sound related experience, can be used to explore factors that affect how well the vibrations make their journey. You might also use the situation to allow children to suggest and make systematic variations. In some cases it will be appropriate that children can explain to supporters and carers some aspects of their work using similar apparatus at home.

What to Prepare

  • A string telephone
  • Several different pots for the ear and mouth pieces
  • Several different lengths and thicknesses of string

What Happens During this Activity

The children can set up the apparatus and explore how it works by sending messages. Encourage descriptions and depictions that focus on the route followed by the vibrations.

We've found it helpful to provide a starter diagram to encourage labelled drawings to explain their findings and reasoning.

Then they can be set the task of suggesting changes and trying them out – perhaps led by more questions that become more specific to focus the thinking.

Teacher: What affects the sound you hear?

Teacher: If I change this one thing then what happens to the sound that you hear?’

This can open all kinds of interesting discussions, and you'll need to have a strategy to draw it to a close.

Perhaps you might risk some topicality by asking:

Teacher: Can you listen in to the messages whilst they are en route, so bugging the telephone?

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