lesson from DIGITAL TECH HUB……………
1. Write a simple message coded using a substitution of a number for each letter; for example, A=1 and Z=26. See how long it takes to ‘crack the code’ or ‘decipher the message’.
Print out two columns containing the letters of the alphabet. Have one column in the correct order. But for the second, offset each letter by 2. For example, A would become C. Using this method, you can code words with each letter offset by 2. So ‘dog’ becomes ‘fqi’.
Students work in a group of three. One student codes a message; for example, reverse the order so that A =26 and Z=1, or have A=1 +1, B=2 +1, Z=26 +1. The other two students decode the message. However, only one of these two students is given the rule.
Discuss how the coding is like encrypting a message with a rule. The student without the rule tries different ways to crack the code (in the way a cyber-criminal might attempt to decipher an email that has been encrypted).
Use a torch (switch it on or off) or hold up a black card and a white card, or use an electronics kit such as littleBits, to communicate a Yes/No answer to a series of written questions.