1. Alan Turing and Code Breaking
Back to the Future – Lesson 1

2. Starter – on whiteboards
Can you think of any famous figures in the world of computing?
What did they do?
Discuss with a partner and be ready to share with the rest of the group.

3. Learning Objectives Learning Objectives Success Criteria
To understand who Alan Turing was
To understand how messages can be encrypted using ciphers.
To understand how to use a cipher key to decipher codes
Success Criteria
To discuss the importance of Alan Turing
To use logical thought to crack codes using a variety of different ciphers
Literacy – Key Words
Cipher
A Cipher is a ‘Secret Message’ often written in code
Decipher
A method to unscramble a cipher so that the ‘Secret Message’ can be understood
Encryption
A method used to scramble messages so that if they are intercepted they cannot be read / understood

4. Learning Habits Reasoning: Noticing details Adapting :
Thinking rigorously, methodically and giving explanations.
Noticing details
Adapting :
Reflecting and making changes
Empathising…
…with feelings and views
Effective use of time
Questioning:
Asking questions to get below the surface
Listening…
…to understand
Imagining…
…how things could be and seeing a range of possibilities
Distilling…
…what you have learnt and what you need to learn
Collaboration:
Working effectively with others
Meta Learning:
Talking about how you have been learning
Imitation:
Picking up good habits from others
Independence:
Working effectively alone
Managing distractions…
…and sustaining concentration
Capitalising:
Using resources purposefully
Making links…
…and recognising relevance
Perseverance:
Overcoming frustration and difficulty
Planning…
…your learning in advance

5. What do we already know?
Who was Alan Turing?

6. Setting the Scene
The world was at war, Britain were fighting the Nazis
German soldiers / government were sending messages to each other in order to communicate strategies.
British Intelligence were managing to intercept these messages – but they were encrypted...
…But if there was a way to decrypt / decipher the messages, then Britain could get vital information about their enemy!
Therefore information / intelligence could be a vital tool in the war!

7. Bletchley Park
Bletchley park was an office set up by ‘British Intelligence’ to try to crack the code so that these messages could be understood.
…and this is were Alan Turing’s story begins!

8. Alan Turing
Alan Turing played a vital role in deciphering the messages encrypted by the German Enigma machine, which provided vital intelligence for the Allies.
He took the lead in a team that designed a machine known as the ‘bombe’ that successfully decoded German messages.
He became a well-known and rather eccentric figure at Bletchley.

9. The Enigma
This is the machine that the Germans invented to write their encrypted messages.
The machine was electric and each time a key was pressed it would turn a series of rotors. These rotors alter the letter pressed so that messages would be scrambled.
The different rotors meant that the encryption machine could be set up one of 100,000 different ways.
So each day, the ‘Enigma’ would be set up slightly differently making it hard for anyone to decrypt, unless they had the key (if, in other words, they knew how it had been set up that day).

10. The Bombe Machine
Turing invented this machine – the Bombe. Messages could be fed into it and the machine could help ‘pin point’ the way that the Enigma was set up when writing that particular message. With this information, British Intelligence could get to work trying to decrypt the messages allowing the British to learn many German secrets. Many of which were instrumental in the War being won!

11. Alan Turning – A sad end to an amazing man
Sadly, Alan was persecuted for his homosexuality.
In the 50’s he faced prison or daily injections to help supress his feelings.
He chose the injection.
A short time later he committed suicide.
Terrible treatment of an amazing man who played a massive part in winning the war and saving us from Nazi rule.

12. Who was Alan Turing?
Mathematician / One of the first Computer Scientists
Created a machine that could help decipher messages sent by the German encryption machine called ‘the Enigma’.
Out of the 100,000 different ways the Enigma could be set up to encrypt messages, the Bombe (Turing’s invention) could reduce these possibilities by working out how the Enigma was set up for each message received.
British Itelligence could therefore decipher the messages much faster, understanding the enemy’s next move and help win the war!

13. Lets Crack Some Code!
We will now exercise some of the logic that Turing used when cracking German messages.

14. Activity – Cracking Code
PigPen Ciphers
What is this message?

15. Pig Pen Ciphers - How they work
This is the KEY
By locating the letters in the key, you can identify the symbols which replace the letter.
To make it harder, the letters can be in different positions to these, so a symbol in one message might represent a different letter in another…without the key it would be very hard to decrypt.

16. Activity Complete one of two worksheets Levels 3-5 Worksheet

17. Plenary Who was Alan Turing? Why do we need to encrypt messages?
What do we need to decrypt a message?