Students how basic encryption types work. The students can send encrypted messages to each other.
| Learning Scenario Identity | |
| Title | JYU28: Caesar Cipher |
| Creator | JYU |
| Length | 90 minutes (2×45 minutes) |
| Main idea/description | Students how basic encryption types work. The students can send encrypted messages to each other. |
| Target group | 3rd-6th grade |
| Curriculum/learning subjects | Mathematics, Physical Education, ICT |
| Competencies | Students will learn how data can be encrypted and decrypted. |
| Teachers’ wellness competences | TC4: Social e-competency |
| Learning Scenario Framework | |
| Pedagogical method | PI3. Enforcing attention and Awareness |
| Software/materials | In this scenario, students will work in pairs to explore encryption through the Caesar cipher method, learning the basics of encryption and how data can be secured. One student encrypts a message, and the other decodes it using a key. Teacher Tools: Use a conferencing tool if remote, allowing students to work in pairs in breakout rooms. The teacher can visit groups to provide guidance and ensure clarity. Clear Instructions: Begin by introducing the concept of Caesar cipher encryption, explaining how each letter in the message is shifted by a certain number of positions in the alphabet (e.g., A becomes D if shifted by 3). Provide visual examples to demonstrate encryption and decryption. Engagement and Breaks: Encourage short breaks after each message is decrypted to reset focus and reduce stress. Gradual Complexity: Start with simple, one-word messages to encrypt and decode, then move to sentences or phrases. Gradually increase the shift number for a more challenging exercise. Collaboration and Reflection: After each encryption/decryption cycle, students should reflect on their process. Ask questions like, “What strategies helped you decode faster?” and “How did you handle more complex shifts?” Suggested Activity:Encrypt and Send: One student encrypts a short message using a shift number they choose. The other student must decode the message using the key (shift number) provided.Error Handling: Introduce an incorrect shift as a challenge. The decoder must identify the error and request the correct key. Closing Reflection:After the exercise, hold a discussion:”How does encryption protect information in real life?””What challenges did you face when decrypting the message?””How would you improve the encryption process for stronger security?” This approach balances hands-on learning, collaboration, and clear incremental steps, minimizing technostress and fostering a positive learning environment. |
| Evaluation tools | The teacher observes the pairs as they start to work on the assignment. The teacher also follows the discussions after each assignment. |
| Learning Scenario Implementation | |
| Learning activities (description, duration, worksheets) | IntroductionA Caesar cipher is like a secret code that changes each letter in a message to a different letter. Imagine you have the alphabet written out in order: A, B, C, D, and so on. To make a secret message, you pick a number and move each letter in the message forward by that many spaces in the alphabet. For example, if we pick the number 3, we would move each letter forward by 3 spaces. So, A becomes D, B becomes E, and C becomes F. If your message was “CAT,” it would turn into “FDW” because:C moves 3 spaces to F,A moves 3 spaces to D,T moves 3 spaces to W. To read the secret message, just move the letters back by 3 spaces! So, “FDW” turns back into “CAT.” It’s like shifting the alphabet to make your words hidden. You can craft your own Caesar cipher wheel with the template in appendix 1. Instructions for its use are also there. Explain that in today’s activity, students will work in pairs to practice encryption and decryption using the Caesar cipher. One student will encrypt a message by shifting letters according to a specific rule, while the other will decode the message using the same shift. This activity simulates how data can be secured through simple encryption. Exercise 1: Encrypting and Decoding Messages in Pairs Pair Up and Assign Roles: One student will take on the role of the “encryptor,” and the other will be the “decoder.” The encryptor will write a short message and use a Caesar cipher to shift each letter by a certain number of positions in the alphabet.The decoder must decrypt the message using the same shift number.Step-by-Step Encryption: The encryptor writes down a simple sentence or word, chooses a shift value (e.g., shifting all letters by 3), and rewrites the sentence by shifting each letter forward in the alphabet. For example, “HELLO” becomes “KHOOR” with a shift of 3.The decoder must figure out the original message by shifting the letters back by the same number. Only the decoder can handle the message at this stage.Mindfulness Breaks: After each message is decoded, encourage a brief mindfulness break, such as stretching or deep breathing. This helps students stay relaxed and focused.Switch Roles: Once the first round of encryption and decryption is complete, the students switch roles. The previous decoder becomes the encryptor, and the task is repeated with a new message.DiscussionAfter completing the first exercise, discuss with the students: “What was challenging about decoding the message?””How did you approach encryption and decryption?””Did you find it easier after switching roles?”Exercise 2: Increasing Complexity Send Longer Messages: Now, the encryptor writes a longer message or a full sentence and increases the complexity by using a larger shift number. For example, shifting by 7 instead of 3.The decoder will follow the same steps as before but must now work with more text and a more difficult shift.Introduce Error Handling: Add an error-correction challenge. The encryptor deliberately makes one small mistake in the cipher. The decoder must identify the error and correct it before decoding the message.If Students Finish Early Students can write encrypted messages for other pairs, further practicing their encoding and decoding skills. This promotes collaboration and helps reinforce the cipher concept.Closing ReflectionOnce all pairs have completed the tasks, hold a final group discussion: “How does encryption help protect sensitive information in real life?””What strategies did you use to decrypt faster?””What did you learn from correcting errors?”This approach fosters collaboration and hands-on learning, reduces cognitive overload through breaks and gradual complexity, and encourages a fun and engaging way to understand encryption basics. |
Appendix 1: Caesar cipher wheel template and instructions for its use.
Instructions for Using a Caesar Cipher Wheel
A Caesar cipher wheel helps you encode and decode secret messages by shifting the letters of the alphabet. Here’s how to use it:
1. Understand the Wheel:
The Caesar cipher wheel has two parts: an inner wheel and an outer wheel.
The outer wheel shows the regular alphabet (A to Z).
The inner wheel also has the alphabet, but this part will rotate to create the secret code.
2. Choose a Shift Number:
First, pick a number for your code. This number tells you how many letters to “shift” by. For example, if you choose the number 3, each letter in your message will be replaced by a letter 3 spaces ahead in the alphabet.
3. Align the Wheels:
Rotate the inner wheel so that the letter A on the outer wheel lines up with the letter that represents your shift number.
For example, if your shift is 3, line up the A on the outer wheel with the letter D on the inner wheel (since D is 3 spaces ahead of A).
4. Encode Your Message:
Write down the message you want to encode.
For each letter in your message, find the letter on the outer wheel.
Look at the letter directly below it on the inner wheel—that’s your encoded letter!
Repeat this for every letter in your message.
Example:
If your message is “HELLO” and you have a shift of 3:
H on the outer wheel lines up with K on the inner wheel.
E on the outer wheel lines up with H on the inner wheel.
L on the outer wheel lines up with O on the inner wheel.
So “HELLO” becomes “KHOOR.”
5. Decode a Message:
To decode a message, align the wheels the same way you did when encoding (for a shift of 3, line A with D).
This time, find each letter of the secret message on the inner wheel, then look up to the outer wheel to find the original letter.
Example:
To decode “KHOOR” with a shift of 3:
Find K on the inner wheel, and it lines up with H on the outer wheel.
Find H on the inner wheel, and it lines up with E on the outer wheel.
So “KHOOR” becomes “HELLO.”
6. Practice and Have Fun:
Try sending secret messages to friends and challenge them to decode them using the Caesar cipher wheel!
