Here is the problem. You must send a spoken message from one end of your table to the other. The listener must not read your lips. You only have two paper cups and a length of string.

Hands up: what is your first idea?

In your group, talk for one minute.

• How might the cups and the string help?
• What could go wrong?
• What will you try first?

Be ready to say one idea out loud.

Each group has the same kit: two paper cups and about two metres of string.

• Make a set-up that sends a quiet spoken message across your table.
• The listener must face away so they cannot read lips.
• Try more than one way. Notice what helps and what does not.
• Then change only one thing (how tight the string is, how you hold the cup, or how loud you speak), test again, and compare.

Three groups will show their working set-up while it is still live.

• Show how you held the cups and the string.
• Send one short word while the listener faces away.
• Say the one idea that made it work, and one thing you changed to improve it.

The idea that made the difference:

Was the string a hollow tube the voice ran through?