Data Representation

Lesson 8

1

StarterI need six volunteers –

Three pupils will be dragons who have 100 million pounds to invest

Three will be developers asking for support of their new exciting app

The dragons will award the money and the rest of the class will debate if this is a correct decision.

2

None of the developers should have been awarded the money

• None of the developers actually demonstrated their app or even talked about it.

• One issue is that developers do not have the funds to create a complete app so we need to develop a prototype

• In this lesson we will use excel to create logic that will encrypt a message.

3

Objective of the lesson• To be able to encrypt and decrypt messages using

Microsoft Excel

• All of you will:

– to discover how encryption works

• Most of you will:

• use Microsoft Excel to encrypt the alphabet.

• Some of you will:

• provide the lookup function to decrypt the alphabet

4

• Create your an app that solves a real world problem

• There is a website that call ‘geeks without bounds’.

5

Homework

Encryption

• Why is encryption important?

• Consider this table

• How would we rename the character length using our new knowledge of binary?

6

Websites and encryption

• Is a password encrypted?

• Why?

• How can we tell if a website has been encrypted?

• Hackers however can bypass all this security by mounting the website system into their computer system file structure.

7

Using Excel to build logic• Download the Excel sheet marked Encryption

from Ilearn.

• In the left hand column the pupils will write in the letters of the alphabet. In the right hand column the pupils will write in their key from the previous homework.

• We need to use a VLookup function to convert the text entered in the cells above.

8

Encryption and decryption• Allan Turing created the first computer capable of

decrypting German messages, does anyone know how he did it?

• Which part of the message provide a key to perform the decryption?

• Do we need to decrypt?• Give examples and reasons behind your

thoughts?• Can you know create a decryption lookup in

excel?

9

Plenary

• What is encryption?

• Why do we need to use it?

• What are the benefits of using excel in this way?

10

• Create a sentence to describe your app and the problem it is trying to solve?

• One paragraph should be enough to explain the idea.

• Extension task is to create a sketch of the app

11

Homework