Lesson Three Code makers and breakers · br eak i ng wos, dct h. T l tu d en o c ir hm a lf b k . T...

Lesson ThreeCode makers and breakers

Teachers’ MaterialsCode Makers and Breakers Lesson PlanFurther Information

Lesson MaterialsAlan Turing and Enigma imagesCodes to Break

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Download this resourcewww.cnduk.org/lesson-3

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AIM To explore the activity of spies andthe use of code breaking fromWorld War Two – the Cuban missilecrisis and beyond.

LESSON OUTCOMESAll students will be able to explainthe origins of code breaking andhow codes work.

Some students will be able toevaluate the challenges faced bycode breakers during the Cubanmissile crisis.

A few students will be able toconsider the legacy of codebreaking and its impact on themodern world.

CONCEPTS TO EXAMINECode breaking, secrecy, prejudiceand discrimination, legacy,intelligence.

Lesson Three: Codemakers and breakers

OVERVIEWStudents will discover the history of code breaking and its significance onevents such as the Cuban missile crisis. They will be able to learn how codebreaking works, and create their own codes. The lesson will enablestudents to consider the moral dilemmas of code breakers. The class willexamine code breakers’ legacy. Students can debate the need for secrecy,intelligence gathering and security in the context of the modern world.

EQUIPMENT NEEDED- Pens- Timeline of Cuban missile crisis (page 12)- List of codes to break- Code breakers PowerPoint (online)- Countdown clock

SUGGESTED TIMEThis is a one hour lesson, but can de differentiated to run over a period oftwo lessons examining each activity in more detail.

ROOM LAYOUT- For group work.- First activity needs space for students to form a ‘debate’ line.

SKILLS- Numeracy- Literacy- ICT- Enquiry- Cooperation and team work

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INSTRUCTIONSStarterUsing Code Breakers PowerPoint teacher to use the debate line slide to consider students’ views of secrecy. Posethe question to the students ‘Does secrecy protect peace?’ If they think it protects peace they stand on one side ofthe room, if they think it doesn’t protect peace they stand on the other side of the room. If they are somewhere inthe middle – they stand somewhere in the middle.

Teacher to then encourage students through questioning to explain why they have the opinion that they do –make sure an appropriate number of responses from each side of the viewpoint is examined.

Main activitiesPut a picture of Alan Turing or Gordon Welchman on the board. Ask students who they think they are. Then put a picture of the Enigma machine on the board – ask students what they think it is.Explain to students using the PowerPoint the historic overview of code breakers at Bletchley Park and leading tothe Cold War.

Split class into USA and Soviet Union.Roleplay activity with a task: Give students a list of codes to break for USA and codes to break for Soviet Union.(There are two sets of codes to use – these can be used for two sets of groups, or alternatives to extend the codebreaking portion of this lesson to fill an hour). They have ten minutes to break each set of codes and must worktogether in order to do this. Countdown the ten minutes – using a countdown clock.

The majority of codes to crack require knowledge from the further information page – they operate on a Caesarcipher, whereby you replace letters with numbers or other letters.

The first one to break the code and complete the action required by the code is responsible for saving the world –if the codes are not broken within ten minutes the Presidents of the Soviet Union and the USA will launch nuclearweapons at each other and both teams will lose.

At end of activity feedback with the students relating to the problems that they faced as a team, and how theyworked together to break the codes – or how they could improve their work in the future.

Students now to create their own codes. They must have a cipher and a way of the code being decrypted when itreaches its destination.

The two teams of USA and Soviet Union stay in place.

Using the timeline of the Cuban missile crisis students pick a significant event in which they would not want theother team to find out about. They then create a code for it.

At the end of the allotted time, students pass the codes to each other and try to break them.

PLENARYStudents to discuss what they think the legacy of the code breakers during the Cuban missile crisis is in today’sworld. Do they think codes still exist? How do they think codes can be used? Are the use of codes a good think?What do they think could be some of the problems with secrecy and intelligence gathering?

DIFFERENTIATION- For the debate line activity give students prompt cards to help them discuss the arguments for and against.- Give students part of the cipher for the list of codes- Give students clues to help them break the codes- Give students a cipher to make their own codes- Use computers to make a cipher either to crack the codes or make their own

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EXTENSION- For the debate line activity, students could be asked ‘Does the use of codes keep our world safe?’ or other

questions on this theme.- Students could argue against their own view to improve their debating skills.- Students can discuss the legacy of the code breakers, including Alan Turing and Gordon Welchman

ENRICHMENT- Take students to Bletchley Park on a trip to find out more about code makers and code breakers- Watch a film – The Imitation Game to learn more about Alan Turing.- Complete the role play or code breaking activities outside the classroom using props, and creative expression.- Read about Gordon Welchman and the invention of ‘The Cloud’ in computer technology- Make and use QR codes to create other forms of codes, these can be done using students’ mobile phones.

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Further information: Code makers and breakers

Since human beings were able to communicate they have attempted to obscure information from each other indifferent ways, in order to keep certain things secret. One way in which to do this is to create a code. Thosemaking the codes are called cryptographers. They give the cipher or way to solve the code to the person who isreceiving the message. In this way all the codes made in the same way can be read. Without the cipher themessage remains secret unless it is broken. Other people who do not have the cipher consider ways in which tobreak or ‘crack’ the code. Code breakers who use logic, intuition and come up with complex mathematicalsystems to uncover the secrets in codes are called cryptanalysts or code breakers.

The Greeks and Romans were some of the first civilisations to use sophisticated ciphers to communicate in secret.The scholar Polybius created a system whereby each letter on a grid would be replaced with a letter from thealphabet in 5x5 grid. A = 1x1 = 2 or N = 3x3 = 9 or T = 4x4 = 16, so the numbers 2, 9, 16 = ANT.

Caesar invented a cipher that shifted the letters of the alphabet by a certain number of letters or numbers i.e. A = 2, B = 3, C = 4 or A = B, B = C, C = D. The more complicated the shift of letters/numbers the morechallenging the cipher and the more difficult it is to break the code. These two systems have formed the basis ofmany codes throughout history.

Modern code makers and breakersCodes continued to advance in a similar way as this until the invention of the telegraph machine and Morse code.This meant that nations were now able to transmit codes across large distances and transmit messages to eachother easily in times of war. However, the codes that they created had to become more complicated as anyonecould listen in and try to work out the cipher for these messages. Codes made by machines started to becomemore popular as technology improved, as these codes enabled complicated ciphers to be created.

To help cryptanalysts in deciphering messages, cipher machines were developed. One of the oldest of these wascreated in the 15th century and called the Alberti Disc. It helped code breakers by using two discs on top of eachother that could be turned to find the corresponding letter. One of the most famous cipher machines was theEnigma machine made by the Germans the 1920s. This machine looked like a typewriter, but each press of abutton indicated a lighted letter. The machine used complex wiring and rotors to create a different letter eachtime. Without the cipher these machines were almost impossible to crack as they were using so many millions ofdifferent letter combinations. In 1932 the first Enigma machine cipher was broken by the Polish General Staff’sCipher Bureau. They were able to do this by receiving intelligence about aspects to do with the cipher, and createa Bombe machine to crack the code. The Enigma machine was then improved upon and new parts were addedto make the code more complicated to crack.

Alan TuringIn World War Two the Germans were using Enigma to transmit messages between their forces. The British hadpreviously set up the Government Codes & Ciphers School which Alan Turing had joined. Alan had some ideasabout how to decipher the now very complicated Enigma machine if intelligence could be received relating toparts of the code that were similar. Alan Turing created a new Bombe machine and from this the British were ableto crack the Enigma machine, and make significant progress in the war. Alan Turing and his team of codebreakers are credited with shortening the overall length of World War Two. After World War Two, Prime MinisterChurchill asked for the information relating to the discovery of the Enigma codes to be kept secret. GovernmentCodes & Ciphers School became the Government Communications Headquarters (GCHQ). Alan Turing was notrecognised for his work, and due to his sexuality, was sentenced to be chemically castrated. He committed suicidein 1954 just before his 42nd birthday. In 2009 Prime Minister Gordon Brown apologised for the appallingtreatment of Turing and in 2013 he was posthumously pardoned.

Code breakers in the Cold WarGCHQ, Mi5, Mi6 and their counterparts in America, the Central Intelligence Agency were very active in theCold War attempting to uncover secrets transmitted and communicated between the USSR and its allies.

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Alan Turing

The Enigma Machine Turing’s Bombe that broke the code

Intelligence gathering is now related to multiple aspects of their work, and the data gathered from bothcodes and satellites images led to the escalation in the Cold War of the Cuban missile crisis. Mixed messagesand a lack of clear communication resulted in some misunderstandings that could have potentially led to theend of the world as we know it.

The internet and ‘The Cloud’ that we use today are a result of the work that mathmaticians like GordonWelchman carried out during the Cold War.

Cryptographers and cryptanalysts still work to make and break codes but now have the ability to usecomplex computer programmes to assist. They would say that there is no unbreakable code, just codes thathave yet to be broken.

Gordon Welchman

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Codes to breakMake sure to give each part of the codes to students to ensure that they will be successful in breaking them. Thecodes can also be differentiated by providing clues. The ciphers for the answers and the answers themselves canbe found at the end of each country set. Do not give these to the students unless you wish to reveal the answersto them. Each word is part of an action that the students must complete to win the game. There are two sets ofcodes for two countries. This enables two rounds or 4 groups.

USA – Part A: No answers

1 2 3 4 5 6 7 8 9 10 11 12 13

A B C D E F G H I J K L M

14 15 16 17 18 19 20 21 22 23 24 25 26

N O P Q R S T U V W X Y Z

2nd wordCode to break: 14, 10, 20, 20, 10, 13, 6

1st wordCode to break: 19, 1, 25

1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25 26


3rd wordCodeword: Bay of Pigs Code to break: UD


B A Y O F P I G S


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4th wordCodeword: Hotline Code to break: YQNL

5th wordCodeword: Time to hurry up, the Soviet Union is winning the arms race.Everyone must support the new atomic age.Atom bombs at the ready.Communists can not rule!Haven't you heard they are getting closer?Expansion of the Soviet Union must be stopped.Ready for nuclear annihilation?



H O T L I N E

USA – Part B: No answers

1st wordCode to break: 4, 15, 15

1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25


2nd wordCode to break: 8,16, 22, 7, 24,19

1 2 3 4 5 6 7 8 9 10 11 12 13

14 15 16 17 18 19 20 21 22 23 24 25 26

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3rd wordCodeword: Disarm Code to break: JBVI

4th wordCodeword: Diplomacy Code to break: XPTSP

5th word





V Vl

AB CD EF

GH I J KL

MN OP QR

UV WX

ST

YZ

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USA – Part A: Answers for teachers

1st word: SAY. Match number to get the correct letter2nd word: MISSILE. Minus 1 from the number to get the correct letter3rd word: TO. Write in the alphabet in order starting at J. If the letter has already been taken in the code wordthen miss that letter out and enter the following letter instead.4th word: YOUR. Enter the alphabet starting with A in A. If the letter in the alphabet appears in the code word‘Hotline’, skip this letter and carry on to the next letter in the alphabet that does not appear in ‘Hotline’.5th word: TEACHER. Take the first letter of each sentence.


B A Y O F P I G S C D E H


I K L M N Q R T U V X Y Z

3rd word

1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25


2nd word

1st word

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1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25


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4th word



U V H O T L I N E W X Y Z

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2nd word

1 2 3 4 5 6 7 8 9 10 11 12 13

Z Y X W V U T S R Q P O N

14 15 16 17 18 19 20 21 22 23 24 25 26

M L K J I H G F E D C B A


D I S A R M B C E F G H J


K L N O P Q T U V W X Y Z

3rd word

1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25


1st word

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USA – Part B: Answers for teachers

1st word: ALL. Minus 3 to the number to get the correct letter2nd word: SKETCH. Enter the letters in alphabetical order but backwards starting with entering A under 26.3rd word: FIVE. Put code word in to cypher so D of Disarm equals A. Then enter the alphabet. If a letter is takenin the code word then enter the next letter in the alphabet.4th word: PEACE. Enter the code word backwards so D for Diplomacy equals Z on the grid. Then enter the restof diplomacy backwards and then the alphabet starting with B underneath Q.5th word: SIGNS. The symbols correspond to the borders around the letters. If the symbol has a dot then it’s thesecond letter in that duo of letters.

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A I Q YB J R ZC K SD L TE M UF N V

G O WH P X

5th word

l

l

l

l

l

l

l

l

l

VV

V

VV

V

VV

l

l

l

l


Z X W V U T S R Q N K J H


G F E B Y C A M O L P I D

4th word

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3rd wordCodeword: Atomic Code to break: BLI

2nd wordCode to break: 21, 6, 2, 4, 9, 6, 19

1st wordCode to break: 20, 5,12, 12

Soviet Union – Part A: No answers

1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25 26


1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25 26



A T O M I C


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4th wordCodeword: Power Code to break: RQTD



P O W E R

5th wordCodeword: My, my – time is starting to run out.Isn't it time we stopped these evil capitalists?Space race has begun.So we must work together.Imperialist Americans must be stopped!Let's get to the moon first!Everyone must support the new atomic age.

1st wordCode to break: 7, 21, 4, 26

2nd wordCode to break: 11, 22, 26, 24, 22

Soviet Union – Part B: No answers

1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25 26


1 2 3 4 5 6 7 8 9 10 11 12 13

14 15 16 17 18 19 20 21 22 23 24 25 26

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3rd wordCodeword: Pacify Code to break: TFOGQNT

4th wordCodeword: Truce Code to break: I J

5th word


P A C I F Y




E C U R T

l

AB CD EF

GH I J KL

MN OP QR

UV WX

ST

YZ

ll

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Soviet Union – Part A: Answers for teachers

1st word: TELL. Match number to get the correct letter2nd word: TEACHER. Minus 1 from the number to get the correct letter3rd word: THE. Write in the alphabet in order starting at G, entering B. If the letter has already been takenin the code word ‘Atomic’ then miss that letter out and enter the following letter in the alphabet instead.4th word: WORD. Enter the alphabet starting with A in A unless it appears in ‘Power’. Skip this letter and carryon to the next letter in the alphabet that doesn't appear in ‘Power’.5th word: MISSILE. Take the first letter of each sentence.


A T O M I C B D E F G H J


K L N P Q R S U V W X Y Z

4th word


A B C D F G H I J K L M N


Q S P O W E R T U V X Y Z

3rd word

2nd word

1st word

1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25 26


1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25 26


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Soviet Union – Part B: Answers for teachers

1st word: DRAW. Plus 3 to the number to get the correct letter.2nd word: PEACE. Enter the letters in alphabetical order but backwards starting with entering A under 26.3rd word: SYMBOLS. Put code word in to cypher so P of Pacify equals A. Then enter the alphabet. If a letter istaken in the code word then miss it out and enter the next letter in the alphabet.4th word: ON. Enter the code word backwards so T for Truce equals Z on the grid. Then enter the rest of Trucebackwards and then the alphabet starting with A underneath U. If a letter is taken in the code word, miss it outand enter the next letter in the alphabet.5th word: PAPER. The symbols correspond to the borders around the letters. If the symbol has a dot then it’s thesecond letter in that duo of letters.

2nd word

3rd word

1 2 3 4 5 6 7 8 9 10 11 12 13

Z Y X W V U T S R Q P O N

14 15 16 17 18 19 20 21 22 23 24 25 26

M L K J I H G F E D C B A


P A C I F Y B D E G H J K


L M N O Q R S T U V W X Z

1 2 3 4 5 6 7 8 9 10 11 12 13


14 15 16 17 18 19 20 21 22 23 24 25 26


1st word

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5th word

A I Q YB J R ZC K SD L TE M UF N V

G O WH P X

l

l

l

l

l

l

l

l

l

VV

V

VV

V

VV

l

l

l

l

Now get students to design their own codes! Use the above ciphers or they can make their own.

4th word


Z Y X W V S Q P O N M L K


J I H G F D B A E C U R T

Lesson Three Code makers and breakers · br eak i ng wos, dct h. T l tu d en o c ir hm a lf b k . T...

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Transcript of Lesson Three Code makers and breakers · br eak i ng wos, dct h. T l tu d en o c ir hm a lf b k . T...