This cipher was invented for the Hebrew alphabet, but it can work with any alphabet.  Many people believe it was used in the Bible and is older than Hieroglyphics! It was later adopted by other cultures, such as the Greeks and Romans, and used to encode messages in their respective languages. This lesson leads students the basics of cryptography.

The student or class will watch a video clip about how to decode a Vigenère Square Cipher.Next students will be able to use the cipher to crack a secret message of their own (teacher provided messages in a hat (not inlcuded)).  One student chooses the word or phrase, the teacher puts the key (word) on the board, that same student will encrypt the message and send it to their partner.  The partner with use the same key word to return the text to plain text revealing the message and send their guess back to their partner. Teachers can edit the message to fit their needs and make adjustments as desired.  This is one mini lesson out of a series of five (part 2) and can be used alone, or with other lessons in the series. Vigenère Square Ciphefrom the past.  Next students will be able to use a Pigpen cipher to crack a secret message of their own.  Teachers can edit the message to fit their needs and make adjustments as desired.  This is one mini lesson out of a series of five. Vigenère Square Ciphe

The student will watch a brief video about the first Morse Code ever sent and how it impacted American communications, even today.  Students will be able to decipher a short Morse Code code (SOS).  They will also learn about Kryptos, an artwork that contains four secretive messages and is placed on display outside of the CIA headquarters. 

The student or class will read about book ciphers and how they work.  Students will then be able to use a cipher provided to crack a secret message.  Teachers can edit the message to fit their needs and make adjustments as desired.  This is one mini lesson out of a series of five, this is lesson four and it can be completed alone, or with any of the other lessons.

During the American Revolution, the Patriots relied on sending coded messages to prevent the British from understanding the actions of the Continental Army. George Washington’s army used this cipher– though it is not a very secure system in its original form. The Patriots adapted it by using a randomized arrangement of the alphabet. This cipher was also used to some extent during the US Civil War.

This lesson is presented by Code.org
Lesson 8: Cybersecurity - Simple Encryption

From the website:
OVERVIEW
"In this lesson, students are introduced to the need for encryption and simple techniques for breaking (or cracking) secret messages. Students try their own hand at cracking a message encoded with the classic Caesar cipher and also a Random Substitution Cipher. Students should become well-acquainted with idea that in an age of powerful computational tools, techniques of encryption will need to be more sophisticated. The most important aspect of this lesson is to understand how and why encryption plays a role in all of our lives every day on the Internet, and that making good encryption is not trivial. Students will get their feet wet with understanding the considerations that must go into making strong encryption in the face of powerful computational tools that can be used to crack it. The need for secrecy when sending bits over the Internet is important for anyone using the Internet."

OBJECTIVE
"Explain why encryption is an important need for everyday life on the Internet.
Crack a message encrypted with a Caesar cipher using a Caesar Cipher Widget
Crack a message encrypted with random substitution using Frequency Analysis
Explain the weaknesses and security flaws of substitution ciphers"

The lesson is mapped out for teachers. It is easy to follow and includes vocabulary to cover, links to the necessary materials, and a teaching guide with background information, tips, and prompts.

AGENDA
Warm Up (10 min)
Classic Encryption - The Caesar Cipher
Activity (35 min)
Part 1 - Crack a Caesar Cipher
Part 2 - Crack a Random Substitution Cipher
Wrap Up (15 min)
Video: Encryption and Public Keys
Discussion
Career Discussion

Overview: This lesson is presented by Code.org
Lesson 8: Cybersecurity - Simple Encryption

From the website:
OVERVIEW
"In this lesson, students are introduced to the need for encryption and simple techniques for breaking (or cracking) secret messages. Students try their own hand at cracking a message encoded with the classic Caesar cipher and also a Random Substitution Cipher. Students should become well-acquainted with idea that in an age of powerful computational tools, techniques of encryption will need to be more sophisticated. The most important aspect of this lesson is to understand how and why encryption plays a role in all of our lives every day on the Internet, and that making good encryption is not trivial. Students will get their feet wet with understanding the considerations that must go into making strong encryption in the face of powerful computational tools that can be used to crack it. The need for secrecy when sending bits over the Internet is important for anyone using the Internet."

OBJECTIVE
"Explain why encryption is an important need for everyday life on the Internet.
Crack a message encrypted with a Caesar cipher using a Caesar Cipher Widget
Crack a message encrypted with random substitution using Frequency Analysis
Explain the weaknesses and security flaws of substitution ciphers"

The lesson is mapped out for teachers. It is easy to follow and includes vocabulary to cover, links to the necessary materials, and a teaching guide with background information, tips, and prompts.

AGENDA
Warm Up (10 min)
Classic Encryption - The Caesar Cipher

Activity (35 min)
Part 1 - Crack a Caesar Cipher
Part 2 - Crack a Random Substitution Cipher

Wrap Up (15 min)
Video: Encryption and Public Keys
Discussion
Career Discussion

***This lesson can be adapted for younger students but material covered aligns best with the current 8th grade Impacts of Computing Standards.