This activity is not only for practicing “solving linear equations” skills, but will give the students a chance to practice their code-breaking skills as well!

The kids will first take an English word and encrypt it using a “shared key” that is given on the worksheet. This shared key is a polynomial with a single variable x. The connection to Math 9 is that the student must use algebraic tactics to create a new value using the polynomial given. Each letter is converted into a number, that number is put through the Polynomial Key, and then the outcome is the encrypted value.

The second part of the worksheet is where they will be given an encrypted word, and they must reverse engineer the given key by using solving equations skills. This will reveal a string of numbers, which then can be paired with their alphabetical counterpart and reveal the original text.

Then, after they had a bit of practice encrypting and decrypting from the first parts of the worksheet, they will have the chance to create their own shared key and message! They will choose a partner in the class, come up with a polynomial that they will use as their “shared key”, and each create an encrypted message for the other. They will then swap messages, and decrypt. Once they have verified that their messages were correct, the assignment is complete!