Copyright © University of Cambridge. All rights reserved.

'Semaphore Signals' printed from http://nrich.maths.org/

Show menu

Semaphore Signals

Semaphore is a way to signal the alphabet using two flags, one held in each hand.

To send a message, your left and right hands have to be in two different positions. You start with both hands pointing down.

Here are the signals for the letters of the alphabet:


A B C D E F G
H I K L M N
O P Q R S
T U Y
J V
W X
Z

Image by kind permission of http://inter.scoutnet.org/


What does this message say?

You might want to send a message that contains more than just letters (exclamation marks, question marks, full stops etc). How many other symbols could you send using this code?

This offers an interesting exploration of systematically finding combinations. Children may need to discuss whether there is a difference between the right hand being at 12 o'clock, compared with the left hand.