Message sent

How do we communicate over vast distances? John Stringer presents activities for you to explore with your pupils. Illustrations: Mark Bergin

Animals communicate with signals that can be seen, heard, smelled or felt. Some fish generate electric fields that can be sensed through the water. Some trees release scents into the air when their leaves are being eaten, warning other trees to produce unpleasant-tasting chemicals. Some animals communicate over huge distances - whales for instance. Only humans, however, have developed different communication technologies, enabling us to talk to people on the other side of the world, to pick up text messages while shopping, and to read the words of people long dead. This project examines three methods we have developed over the centuries to communicate with one another.

Bright beacons

Ask pupils to:

* Look on local maps. Where was the nearest beacon to your school?

* Use the internet and CD-Roms to research recent events that were marked with beacon fires.

* Estimate how long it took to send a beacon message warning of the imminent arrival of the Armada from Plymouth to London in 1588. Suppose that the beacons were about five miles apart, and each had to be seen clearly before the next fire could be lit.

* Find and read the passage about beacons in William Golding's The Lord of the Flies. Why does the beacon fail to attract passing ships?

Smoke signals

In the earliest times, fire and smoke were used to signal over long distances. Beacon fires featured in the Iliad stories 3,000 years ago, and the Romans established chains of high posts with fire-baskets at the top. In 1588, the first sighting of the Spanish Armada was signalled across England in hours by fires.

People seeing lighted beacons or smoke signals have to know what they mean, so a code has to be agreed beforehand - the plains Indians of North America, for example, used agreed smoke signals to send messages.

Modern beacons are powered electronically and send simple messages. Sometimes they use sound and may not be visual at all. Such messages often say: "Here I am." They may signal a hazard or a runway to an aeroplane, or the position of someone lost at sea.

The word "beacon" survives in many place names, such as Barr Beacon in Birmingham, and Beacon Hill in Boston, Massachusetts, where fires once warned approaching ships of hazards.

Morse code

"I wish that in one instant I could tell you of my safe arrival," wrote the American Samuel Morse to his mother in 1811. Morse was in London, and his letter would take four weeks to reach her.

On the steamship home, Morse realised that an electrical circuit could be used to carry a message. He devised a code of "shorts" and "longs", or dots and dashes.

His code could be seen as a flashing light or a moving needle, or heard as a series of clicks coming from a special device. It could even be printed on paper tape. Messages could be sent instantly, making the invention popular with US railway companies, who used it to check on the progress of their trains. Newspaper editors seized on it as a way of transmitting news quickly. Soon all major cities were linked by the system.

The Morse alphabet

In Morse code, a dash is three times the length of a dot. A space as long as a dot separates letters; words are separated by a three-dot space, and sentences by a seven-dot space. A really fast Morse operator can send 30 words a minute.

Get tapping

Ask pupils to:

* Make a simple Morse circuit that will cause a bulb to flash. They will need a springy switch. Remember it is the length of the dot and dash that matters.

* Send a message using the Morse code. They could use sound or light. What's the longest possible distance they can communicate over?

* Use plastic mirrors to flash messages to one another (don't shine light into anyone's eyes).

* Research the history of semaphore: flags, discs and even the sails of windmills were used to send messages.

* Test the different ways in which they can send the same message. Which would be best in bad weather, at night or at sea?

Global messages

An e-mail is a message that travels from one computer to another using the World Wide Web.

You need a computer, a telephone line and an e-mail address. Your message may be just a typed note or letter, or you can attach spoken words, music, photographs and even moving pictures.

The computer's modem converts the message to electrical signals that can travel by telephone. It also receives messages and converts them back into data that your computer can display as text or pictures.

A server is a powerful computer that directs the message to the correct e-mail address. E-mails are stored on the server in a "mailbox".

The sender's address is displayed so that you can send a reply. It's easy to copy the message or forward it to other people.

Sending an e-mail to everyone listed in your "address book" can be as quick as sending a message to one person.

Forming attachments

Ask pupils to:

* Look at e-mail addresses on websites. An e-mail can only arrive if the address is correct. Write brief e-mail messages to a friend, to a partner school, and to someone famous. Where do you get their addresses from? How do you know they are accurate?

* Write an e-mail with an attachment. Attach a picture you have drawn, a photograph of your class or a piece of music you have composed.

* Using your e-mail software, how many different ways can you find to reply to a friend's e-mail?

* Forward an e-mail to several people. Include an attachment with news of hobbies and interests you all share and ask them to reply.

TEACHER NOTES

Beacon fires

The advantage of a beacon fire is that it can be seen from far away. The disadvantage is that the sender and receiver have to agree in advance what it means. In most cases there can only be a single function.

The Greeks elaborated on this with a system of beacon fires in wall notches. The placing of the fires was to an agreed code, and viewers who had the code could read the message.

Beacon Hill, Beacon End and the Brecon Beacons all feature in the national road atlas. Are there other examples near you?

Chains of beacons marked the end of the Second World War and the Millennium. There may be similar plans in your community for the Queen's Golden Jubilee on June 34.

Morse code

Samuel Morse's code was only one of several that were devised for the electric telegraph. But Morse's code had the advantage of accuracy and simplicity, and his use of electromagnetic relays ensured that the signal did not diminish over great distances. He won financial support from the US Congress and in 1844 he sent the famous message: "What hath God wrought" from Washington DC to Baltimore.

A simple Morse circuit can be constructed using a battery, a bulb, a length of wire and a "push-to-close" switch. The message can be sent from the switch over a long length of wire to the bulb. Pupils can also use an ordinary torch and a shutter. You can extend this into a technology project by getting pupils to devise a way of using the torch to send a signal. Aldis lamps flash with a shutter that looks like a Venetian blind.

Global messages

E-mail - or electronic mail - has its own conventions, as well as its own shorthand. Children will be keen to learn about them. Compare the shorthand of e-mail with the conventions of text messaging. Pupils will quickly discover that accuracy is the key to the use of e-mail. One incorrect letter in an address will result in the message going astray or being returned undelivered; one incorrectly pressed key will send a private message to your entire address book.

Encourage the children to write real messages to real people. Some fan websites offer automatic acknowledgment, which means that you will get a reply - of a sort - from a famous personality.

Teach children about the potential dangers of e-mail relationships and open chat rooms; and not to reveal their ages, home addresses or any other personal details.

Children could look further at other ways of communication, especially for those with physical disabilities, by using their computers.

Websites

Some links for further exploring the themes of communication are suggested below:

* to find out more about Braille go to: www.nfb.orgbrailco.htm;

* to visit sign-language site that includes video of alphabet, numbers and common English words: www.dpa.org.sgsignlang;

* to visit the official NASA site for the Voyager project (Voyager spacecraft are carrying messages into space in the hope of contacting life on other planets) go to: http:vraptor.jpl .nasa. govvoyagervoyager.html;

* to see the contents of the Voyager message go to: http:vraptor.jpl.nasa. govvoyagerrecord.html.

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