Semaphore signals

Semaphore is a way to signal the alphabet using two flags. You might want to send a message that contains more than just letters. How many other symbols could you send using this code?
Age
7 to 11
Challenge level
filled star filled star empty star
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

Problem

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:

Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals

Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals

Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals

Semaphore Signals
Semaphore Signals
Semaphore Signals

Semaphore Signals
Semaphore Signals

Semaphore Signals
Semaphore Signals

Semaphore Signals

Image by kind permission of scoutnet

 

What does this message say?

 

Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals
Semaphore Signals

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?