How can we improve the speed of a (deterministic) primality test? Created by Brit Cruise.

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.

There were many black women who worked as code breakers at Arlington Hall during World War II, including Elsie Scott, Sue Bailey Thurman, and Genevieve Collins. These women faced significant challenges and discrimination due to their race and gender, but they made significant contributions to the war effort through their work as code breakers.

This video module presents an introduction to cryptography - the method of sending messages in such a way that only the intended recipients can understand them. In this very interactive lesson, students will build three different devices for cryptography and will learn how to encrypt and decrypt messages. There are no prerequisites for this lesson, and it has intentionally been designed in a way that can be adapted to many audiences. It is fully appropriate in a high school level math or computer science class where the teacher can use it to motivate probability/statistics or programming exercises. nteractive lesson, students will learn to build the cryptography devices and will learn how to send and ''crack'' secret messages.

This lesson plan can be used for teaching and reinforcing the idea of encryption for middle school students.

Brit explains the Caesar cipher, the first popular substitution cipher, and shows how it was broken with "frequency analysis". Created by Brit Cruise.

Students will examine the history and culture of the Choctaw Native Americans, as well as the story of the Code Talkers in WW1, in order to memorialize one of the Choctaw Code Talkers. 

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.

Women code-breakers changed the course of WWII by cracking Japanese codes that revealed the movements of people and supplies in the Pacific Islands. In this lesson, students will learn how specific information discovered led to a turning point when cryptographers were able to pinpoint the plans of the Pearl Harbor Attack’s “architect”, Admiral Yamomoto.Students will examine videos and articles to find out more about this episode in history. In pairs or small groups, they’ll look at the US Post Office’s newly revealed stamp commemorating it. They’ll identify what they think are the pros and cons of the stamp and then design their own. 

This breakout activity provides teachers and students an interactive way to demonstrate their learning about cryptography, code-breaking, and historic ciphers. Clues are provided, along with additional hints you can choose to provide to students so that students solve ciphers and learn what time their army is planning to raid the enemy camp.

In this lesson, students will learn about one of the most significant and successful spy rings in American History. They will also actually conduct some of the same techniques and demonstrate them to the rest of the class.

WW2 Encryption is explored with a focus on the Enigma. Read more here. Created by Brit Cruise.

A quick outline of how & why it works. Created by Brit Cruise.

Introduction to a key result in elementary number theory using a visualization with beads. Created by Brit Cruise.

Can you tell the difference between actions based upon flipping a coin and those based upon blind guessing or simulating randomness? This short video examines the frequency stability property. Created by Brit Cruise.

American performer Josephine Baker used her star-status access to spy for the Allies in WWII and convey information to the Allies by using invisible ink on her sheet music. We’ll look at a few methods that can be used to hide messages “in plain sight”?

Students will learn about Mask Letters and their use in the Revolutionary War, then they will make masks and messages of their own and discuss the pros and cons of this method of sending and receiving secret messages.