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Teachers: Literacy: Text

Last Updated: Wednesday March 30 2005 14:51 GMT

Cracking the code

Overview

Who Can Crack the Leonardo da Vinci code?
A code-cracking scroll, a foil mirror and a set of riddles are the tools supplied to solve the mystery in a new children's book about Leonardo Da Vinci.

The book, Who Can Crack The Leonardo Da Vinci Code?, by Austrian writer Thomas Brezina, is released in the UK in May.

It invites readers to solve an interactive adventure to be transported back in time.

Students look at the reasons for using codes and learn about the Morse code and Egyptian hieroglyphs.

Learning aims
  • What is a code or cipher?
  • Why are they used?
  • What is Morse code?
  • What are Egyptian hieroglyphs?
  • How does the alphabet act as a code?
Icebreaker

A code or cipher is a system of letters or symbols standing for information. There are rules for cracking or deciphering the code.

Ask students:

  • Why do people use codes? For secrecy, brevity

  • How many famous codes can you name?
    • Morse code - using a series of dots, dashes, and spaces to represent the alphabet and numbers.
    • Egyptian hieroglyphs - the Greek word hieroglyphica means 'sacred carvings.' These elaborate symbols were found on the walls of temples and monuments from 3100BC. Individual hieroglyphs represent distinct sounds, just like the letters in the English alphabet.
    • Bible code - an American journalist says he can see into the future using a 3,000 year old code, hidden in the Bible.
    • Genetic code - it shows the order of DNA in cells.
    • The Da Vinci Code - the name of a book by Dan Brown about two code-breakers trying to track down the truth behind the Holy Grail. It has been condemned by some Catholic churchmen.

Warm up

Outline the history of Morse code to students:

Tapping out Morse code
The Morse code was invented in America in 1835 by American painter Samuel Morse and Alfred Vail.

It became the first form of radio communication and a global language which could be transmitted by flashes of light as well as sound.

It was used to send and receive military messages during several wars and was used by sailors up until 1997.

The first and most famous use in the UK of the classic "dot-dot-dot dash-dash-dash dot-dot-dot" SOS emergency signal was from the Titanic on its doomed maiden voyage in 1912.

It also famously led to the arrest of British murderer Dr Crippen in 1910. He fled the UK by boat to Canada but, thanks to a Morse Code radio message sent across the Atlantic, he was arrested on arrival.

MORSE CODE CRACKER
Morse

Pair work. Each student writes a sentence-long message for their partner, without showing them.

Using the Morse code-cracker, they translate their messages into a series of dots and dashes.

They swap messages and decipher them.

Morse code cracker
A .- N -. Zero -----
B -... O --- 1 .----
C -.-. P .--. 2 ..---
D -.. Q --.- 3 ...--
E . R .-. 4 ....-
F ..-. S ... 5 .....
G --. T - 6 -....
H .... U ..- 7 --...
I .. V ...- 8 ---..
J .--- W .-- 9 ----.
K -.- X -..- . .-.-.-
L .-.. Y -.-- , --..--
M -- Z --.. ? ..--..

Main activity

Explain to students:

An alphabet is a bit like a code. The shapes of the letters stand for sounds. The sounds are used to make words. Words communicate an idea from one person to another using the alphabet code.

Unless you can crack the code, or know the language, you will not be able to understand the other person.

One famous alphabet that took centuries to crack is that of the ancient Egyptians.

The meaning of the mysterious Egyptian hieroglyphs baffled the greatest minds in the world until the discovery of the Rosetta Stone in 1799.

The slab has the same piece of text inscribed on it three times; in Greek, demotic (another type of Egyptian alphabet used for day-to-day scribbling) and hieroglyphics. It is the equivalent of a dictionary and shows how individual hieroglyphs represent syllables.

E.g. the word belief can be broken down into two syllables, 'bee-leaf'. Instead of writing the word alphabetically, you could draw the image of a bee and a leaf.

Egyptian hieroglyphs spell the pharoh Rameses
This hieroglyph spells Rameses - an Egyptian pharaoh. The first syllable is represented by a picture of the sun, pronounced 'ra'. The remainder of the word is spelt in a more normal fashion.

Activity: Students devise their own hieroglyphic code. They start by inventing a key with each letter of the alphabet represented by a simple drawing.

They could look at the Egyptian alphabet for inspiration. Click on the link in the green box on the right hand side.

Students answer these questions:

  • Who would use your code?
  • When would they use it?
  • Where would they use it?
  • Why would they need a code?
  • What would be the advantages of communicating in code?
  • How would your code be transmitted? E.g. radio, post, internet, flashing light.
Using their key, students write an encoded message for their partner to decipher.

Extension activity

Egyptian writing uses more than 2,000 hieroglyphs. Each one represents a common object found in ancient Egypt. Some hieroglyphs represent the sound of the object.

This rebus puzzle says 'I love school'
This rebus puzzle says 'I love school'

Using the notion of an image representing a sound, students devise rebus puzzles like this one for each other to solve.

A rebus is a picture puzzle where sounds are represented by images. The puzzle makes sense when you read it out loud.

Plenary

Students present their codes to the class. They explain who would use the code, when, where and why it would be used, how it would be transmitted and what would be its benefits.

Recap on the notion that a code or cipher is a system of letters or symbols standing for information and that there are rules for cracking or deciphering the code.

Reiterate the notion that the alphabet is a type of code.

Teachers' background

World War II code-cracking

In 2001, the release of the film Enigma sparked great interest in the world of the boffins who broke Nazi Germany's secret wartime communications codes. The title referred to a piece of spook hardware, like a typewriter, which encrypted secret messages.

As a result of the information gained through this device, it has been claimed, World War II was shortened by two years.

Code-breakers at Bletchley Park deciphered messages written on German and Japanese code machines like Enigma, Purple and Geheimschreiber (secret writer).

The Germans thought Enigma's codes were impossible to crack as the machine was so complex, the odds against breaking the codes were 150 million to one.

Elizabeth I's code-crackers

Queen Elizabeth I was the target of plotters who wished to replace her with the Catholic Queen Mary. Ruthless spymaster Francis Walsingham oversaw her secret service.

Their intelligence work involved learning how to break the different codes used by plotters. Often, letters of the alphabet were shuffled in a certain sequence or substituted with numbers, symbols or signs of the zodiac.

Spies had to learn not only how to decipher code but also how to write it themselves.

Some codes could only be understood by placing a sheet of paper punched with holes over the top so that just the relevant letters making up the message could be read.

Some letters were written in invisible ink. Using milk or lemon juice, the secret message could be read as the page was warmed over a candle and the letters appeared.

Unimportant text in normal ink was often written alongside the hidden message to throw spies off the scent.

Dr Who and Morse code

Dr Who doesn't carry cash because he can crack safes. He also knows Morse code.



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