The Caesar Cipher - Crack the Code Activity with Free Printable
- 42 minutes ago
- 2 min read
What's the Caesar Cipher?
The Caesar Cipher is a way of changing words into a secret code - this is called encryption. The encryption is very simple; all of the letters in the alphabet are moved - or "shifted" - a certain number of places along to the right. For example, if you choose to shift the letters of the alphabet by 3 places, A becomes D, B becomes E, C becomes F, and so on:
Why is it called the Caesar Cipher?
The Caesar Cipher was named after Julius Caesar, leader of Ancient Rome in 49BC. Julius Caesar used this simple cipher to encode his messages. This way any important notes could only be read by those who knew how many letters to shift the alphabet by. If Julius Caesar's letters fell into the wrong hands, his enemies wouldn't be able to read them. Mostly, Julius Caesar used a shift of three letters (as demonstrated in our activity below).
How do I decrypt the Caesar Cipher?
It's easy to crack (or "decrypt") the code created by a Caesar Cipher - IF you know how many letters the code is shifted by. Simply, you write the alphabet along a long line, then underneath you write the alphabet again, this time shifted a number of places (three places, if you're decrypting one of Julius Caesar's messages).
If you don't know how many places to shift the alphabet by, the job becomes a lot harder. This is because there are 25 different encryptions available in the Caesar Cipher (because there are 25 letters in the alphabet that you could shift the order by)!
Activity - Decrypt the Caesar Cipher
Check out the activity sheet in the image below (or download it using the links at the bottom of the article). Can you use the Cipher key at the top to decrypt the coded message underneath? What does the message say?
Activity - Create your own Caesar Cipher
Once you've cracked the code, you can use a grid just like the one below to create your own cipher. Don't forget, you need to decide how many places to shift the letters in the alphabet to create your cipher - you can shift them up to 25 places!
Now you can write a coded message using your cipher. Can you get your friends and family to decrypt your message? If they're new to the game, make sure to tell them how many places to shift the alphabet by. If they're masters at cracking codes, put them to the test by not telling them how many places to shift the alphabet by - see how long it takes them to crack the code.
Answers:
Managed to decrypt the message? Check whether you've got it right below:
Download this activity:
Download a free printable of this activity right here*:
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