Help children learn the semaphore system.
"The current flag semaphore system uses two short poles with square flags, which a signalman holds in different positions to signal letters of the alphabet and numbers.
The signalman holds one pole in each hand, and extends each arm in one of eight possible directions.
Except for in the rest position, the flags do not overlap.
The flags are colored differently based on whether the signals are sent by sea or by land.
At sea, the flags are colored red and yellow (the Oscar flag), while on land, they are white and blue (the Papa flag)." (Wikipedia)