A sailing ship displaying signal flags

Learn about the way ships have communicated at sea for over a century, and still do. Colour in your own set of pixel puzzle flags. This kind of bit map image is one way computers can store images. Then start sending your own messages from your bedroom window.

International maritime signal flags are flags used by ships to communicate. An individual flag can represent a letter or number but they can also be used to communicate an agreed standard phrase. For example the flag for the letter E (given the name ‘Echo’ in the phonetic alphabet) is also used to mean “I am altering my course to starboard”.

Letter E from Wikipedia’s page on signal flags.

Of course this means that for effective communication everyone needs to know in advance what the code flags mean, and the rules for using them.

Activity – pixel puzzle version of signal flags

There are lots of ways to store images on computers but one simple way is to split the image into a grid of squares (pixels) and then gave each little square a number corresponding to its colour. Such an image is called a bit map image.

Elisa has created a series of pixel puzzles, one for each flag. Use the key to colour in each pixel in the correct colour (so a kind of colour by number puzzle) and create your own set of flags, then cut and paste them to spell out messages.

More activities around maritime signal flags as well as a different way to describe and store images

Lots more pixel puzzles