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Send your own messages using signal flags!
Long before radio communication, mariners used signal flags to communicate between ships. An international code still exists at sea today. Each flag stands for a letter or number. String multiple flags together and one can send a message as far as the eye can see. If flown by themselves, single signal flags can also mean special codes.
With the materials below, you can get started on two different activities: Activity 1: Decipher Signals and Activity 2: Print, Cut, and Create Messages.
Activity 1: Decipher Signals

International Code of Signals alphabet flags and number pennants. Print this key or use the gallery above to decipher messages.
Below are several messages encoded using signal flags. Use the online gallery above or the printable key to solve each message. The answers are in collapsible items that follow each code!

Hint: An abbreviation.
Solution
Answer: NPS
Short for National Park Service.

Hint: A greeting.
Solution
Answer: HELLO
How are you?

Hint: A call sign.
Solution
Answer: NTTH
Radio stations have call signs used to identify them. This is true for television, FM radio, and even ships like USS Cassin Young. During World War II Cassin Young operated with the call sign November Tango Tango Hotel, or, NTTH.

Hint: A revolutionary city.
Solution
Answer: BOSTON
Boston is a city of revolutions and home to three National Park units.

Hint: What you can find at the Charlestown Navy Yard.
Solution
Answer: 2 SHIPS
The Charlestown Navy Yard is home to two ships: USS Constitution and Cassin Young.

Hint: Wildlife in the harbor.
Solution
Answer: 4 WHALES
Between Boston Harbor and Cape Cod, the Stellwagen Bank National Marine Sanctuary is home to a wide variety of wildlife, including whales.
Activity 2: Print, Cut, and Create Messages
Using the files below, print out the signal flag sheets. Cut out each flag and arrange any number of them to form a message you want to send. You can glue your message to paper or even hang them on a string.
Where this belongs
- Boston National Historical Park
Where this page came from
This page was imported from National Park Service. Produced by the U.S. National Park Service and, as a work of the United States government, in the public domain.
Nobody has written it yet — it is the source material at a new address, which is why search engines are asked to skip it and why no one earns from it. It is up for grabs: take it on, and it is yours to rewrite and to earn from.
In these publicationsBoston National Historical Park
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
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