Learning objective
Cryptography
Cryptography & Unplugged Encryption
Unlocking the secret science of codes, ciphers, and digital data scrambling. Students progress from physical substitution ciphers to public-key encryption and modern hashing algorithms.
Secret Symbols & Keys
Understand that messages can be encoded using symbol substitution keys.
Let's Go!
Learn
Cryptography is the science of secret writing! When you turn readable text (plaintext) into a secret code (ciphertext), you are 'encrypting' it. Anyone with the secret 'key' can turn it back into readable words ('decrypting'). In computing, symbols and codes allow people to transmit private messages. As you explore the interactive Cipher Wheel Simulator below, focus on how to decode an unknown short secret message using a substitution key without teacher assistance.
Mathematical definition of the Caesar shift with alphabet wrap-around:
Expected distribution across 100,000 words in standard English corpora:
| Letter | Freq % | Letter | Freq % |
|---|---|---|---|
| E | 12.70% | T | 9.06% |
| A | 8.17% | O | 7.51% |
| I | 6.97% | N | 6.75% |
| S | 6.33% | H | 6.09% |
| R | 5.99% | D | 4.25% |
Mathematical foundation of public/private key trapdoor one-way functions:
Apply Simulator Skills โข Try it yourself
Decode the Spy Message
๐ Open a practice space
๐ Student Project GuideSuccess Criteria & WAGOLL (What A Good One Looks Like)
๐ฏ Task Success Criteria (Rubric)
Matches a symbol on a decoder sheet to its matching alphabet letter.
Encodes a 4-letter word using a grid-based symbol key.
Decodes an unknown short secret message using a substitution key without teacher assistance.
Creates a custom symbol substitution key and explains why keeping the key secret is necessary for privacy.
๐ What A Good One Looks Like (WAGOLL)
โญ Mastering StandardWhen you finish creating your project in your software, copy the share link or take a screenshot and publish it onto your student portfolio website!
Reflect
Learning check
Teacher setup, curriculum links and progress descriptors
Spark support
Routine: See, Think, Wonder
Teacher notes: Facilitate the See, Think, Wonder routine for 2โ3 minutes. Encourage students to connect the prompt to Form (Symbols and codes allow people to transmit private messages.).
Achievement pathway
- Foundation: Matches a symbol on a decoder sheet to its matching alphabet letter.
- Developing: Encodes a 4-letter word using a grid-based symbol key.
- Secure: Decodes an unknown short secret message using a substitution key without teacher assistance.
- Mastering: Creates a custom symbol substitution key and explains why keeping the key secret is necessary for privacy.
Curriculum links
Curriculum strand: Everyday Digital Skills & Computational Science
Outcome: CY.01.B.1.1 โ Understand that messages can be encoded using symbol substitution keys.
PYP: Form ยท Symbols and codes allow people to transmit private messages.
Learner profile: Inquirer
Competency tags
Gate support
Accessibility alternative: Students may verbally explain or point to the correct answer for "In cryptography, what is a 'Key'?" with a teacher or teaching assistant.
Teacher override: allow
Locked level
Level 2: The Caesar Shift Cipher
Complete the previous learning check to unlock this next level.
The Caesar Shift Cipher
Apply numeric shift algorithms (Caesar Cipher) to encode and decode text.
Learning objective
Students will shift alphabet letters by a numerical key (+3, -3) to encrypt and decrypt messages.
Let's Go!
Learn
The Caesar Cipher is one of the oldest mathematical codes! You pick a shift number (like +3). 'A' becomes 'D', 'B' becomes 'E', and 'C' becomes 'F'. To read it, the recipient reverses the shift by subtracting 3. In computing, mathematical shifts create predictable algorithmic patterns. As you explore the interactive Cipher Wheel Simulator below, focus on how to decrypt a message using a Caesar shift of -3 and handles wrap-around letters (e.g. 'Z' shifting forward to 'C').
Mathematical definition of the Caesar shift with alphabet wrap-around:
Expected distribution across 100,000 words in standard English corpora:
| Letter | Freq % | Letter | Freq % |
|---|---|---|---|
| E | 12.70% | T | 9.06% |
| A | 8.17% | O | 7.51% |
| I | 6.97% | N | 6.75% |
| S | 6.33% | H | 6.09% |
| R | 5.99% | D | 4.25% |
Mathematical foundation of public/private key trapdoor one-way functions:
Apply Simulator Skills โข Try it yourself
Caesar Cipher Wheel Challenge
๐ Open a practice space
๐ Student Project GuideSuccess Criteria & WAGOLL (What A Good One Looks Like)
๐ฏ Task Success Criteria (Rubric)
Counts forward 3 alphabet steps from 'A' to find 'D'.
Encrypts a word using a Caesar shift of +3.
Decrypts a message using a Caesar shift of -3 and handles wrap-around letters (e.g. 'Z' shifting forward to 'C').
Calculates reverse shift keys and explains why small shift keys are vulnerable to brute-force cracking.
๐ What A Good One Looks Like (WAGOLL)
โญ Mastering StandardWhen you finish creating your project in your software, copy the share link or take a screenshot and publish it onto your student portfolio website!
Reflect
Learning check
Teacher setup, curriculum links and progress descriptors
Spark support
Routine: Zoom In
Teacher notes: Facilitate the Zoom In routine for 2โ3 minutes. Encourage students to connect the prompt to Function (Mathematical shifts create predictable algorithmic patterns.).
Achievement pathway
- Foundation: Counts forward 3 alphabet steps from 'A' to find 'D'.
- Developing: Encrypts a word using a Caesar shift of +3.
- Secure: Decrypts a message using a Caesar shift of -3 and handles wrap-around letters (e.g. 'Z' shifting forward to 'C').
- Mastering: Calculates reverse shift keys and explains why small shift keys are vulnerable to brute-force cracking.
Curriculum links
Curriculum strand: Everyday Digital Skills & Computational Science
Outcome: CY.01.B.1.2 โ Apply numeric shift algorithms (Caesar Cipher) to encode and decode text.
PYP: Function ยท Mathematical shifts create predictable algorithmic patterns.
Learner profile: Thinker
Competency tags
Gate support
Accessibility alternative: Students may verbally explain or point to the correct answer for "Using a Caesar Shift of +1, what does the word 'CAT' become when encrypted?" with a teacher or teaching assistant.
Teacher override: allow
Locked level
Level 3: Frequency Analysis & Code Cracking
Complete the previous learning check to unlock this next level.
Frequency Analysis & Code Cracking
Use letter frequency statistics to crack simple substitution ciphers without a key.
Learning objective
Students will count letter occurrences in an encrypted text to identify the most common letter ('E') and crack the cipher.
Let's Go!
Learn
Codebreakers don't guess blindlyโthey use statistics! In English, the letter 'E' appears about 12% of the time, followed by 'T' and 'A'. If an encrypted message has the letter 'X' appearing dozens of times, 'X' is almost certainly 'E'! In computing, pattern analysis and data statistics reveal hidden structures. As you explore the interactive Cipher Wheel Simulator below, focus on how to use frequency analysis to deduce the shift key and decrypt an intercepted ciphertext without being given the key.
Mathematical definition of the Caesar shift with alphabet wrap-around:
Expected distribution across 100,000 words in standard English corpora:
| Letter | Freq % | Letter | Freq % |
|---|---|---|---|
| E | 12.70% | T | 9.06% |
| A | 8.17% | O | 7.51% |
| I | 6.97% | N | 6.75% |
| S | 6.33% | H | 6.09% |
| R | 5.99% | D | 4.25% |
Mathematical foundation of public/private key trapdoor one-way functions:
Apply Simulator Skills โข Try it yourself
Be a Cryptanalyst
๐ Open a practice space
๐ Student Project GuideSuccess Criteria & WAGOLL (What A Good One Looks Like)
๐ฏ Task Success Criteria (Rubric)
Identifies that 'E' and 'T' are the most common letters in English books.
Tallies letter counts in a short encrypted paragraph to find the most frequent symbol.
Uses frequency analysis to deduce the shift key and decrypt an intercepted ciphertext without being given the key.
Explains why simple substitution ciphers are easily broken by computers using statistical analysis.
๐ What A Good One Looks Like (WAGOLL)
โญ Mastering StandardWhen you finish creating your project in your software, copy the share link or take a screenshot and publish it onto your student portfolio website!
Reflect
Learning check
Teacher setup, curriculum links and progress descriptors
Spark support
Routine: Parts, Purposes, Complexities
Teacher notes: Facilitate the Parts, Purposes, Complexities routine for 2โ3 minutes. Encourage students to connect the prompt to Connection (Pattern analysis and data statistics reveal hidden structures.).
Achievement pathway
- Foundation: Identifies that 'E' and 'T' are the most common letters in English books.
- Developing: Tallies letter counts in a short encrypted paragraph to find the most frequent symbol.
- Secure: Uses frequency analysis to deduce the shift key and decrypt an intercepted ciphertext without being given the key.
- Mastering: Explains why simple substitution ciphers are easily broken by computers using statistical analysis.
Curriculum links
Curriculum strand: Everyday Digital Skills & Computational Science
Outcome: CY.02.B.1.1 โ Use letter frequency statistics to crack simple substitution ciphers without a key.
PYP: Connection ยท Pattern analysis and data statistics reveal hidden structures.
Learner profile: Knowledgeable
Competency tags
Gate support
Accessibility alternative: Students may verbally explain or point to the correct answer for "You intercepted a secret message where the letter 'Q' appears 25 times, far more than any other letter. What should you guess 'Q' represents?" with a teacher or teaching assistant.
Teacher override: allow
Locked level
Level 4: Symmetric vs Asymmetric Encryption
Complete the previous learning check to unlock this next level.
Symmetric vs Asymmetric Encryption
Differentiate between single-key (symmetric) and dual-key (public/private key) encryption.
Learning objective
Students will demonstrate how public and private key pairs allow secure web communication without sharing secret passwords.
Let's Go!
Learn
Symmetric encryption uses ONE key to lock and unlock. But how do you share that key safely online? Asymmetric encryption solves this with TWO keys: a PUBLIC key (like an open padlock anyone can use to lock a box) and a PRIVATE key (the only key that unlocks it)!
Mathematical definition of the Caesar shift with alphabet wrap-around:
Expected distribution across 100,000 words in standard English corpora:
| Letter | Freq % | Letter | Freq % |
|---|---|---|---|
| E | 12.70% | T | 9.06% |
| A | 8.17% | O | 7.51% |
| I | 6.97% | N | 6.75% |
| S | 6.33% | H | 6.09% |
| R | 5.99% | D | 4.25% |
Mathematical foundation of public/private key trapdoor one-way functions:
Apply Simulator Skills โข Try it yourself
Public Key Padlock Simulation
๐ Open a practice space
๐ Student Project GuideSuccess Criteria & WAGOLL (What A Good One Looks Like)
๐ฏ Task Success Criteria (Rubric)
States that websites use secret encryption to protect credit cards and passwords.
Explains the problem with symmetric keys: if you send the secret key over the internet, someone could intercept it.
Role-plays Public/Private key exchange using the 'Padlock & Box' analogy (Public key = open padlock everyone can lock; Private key = secret key only you hold).
Explains how HTTPS and SSL certificates use asymmetric encryption to establish secure internet connections.
๐ What A Good One Looks Like (WAGOLL)
โญ Mastering StandardWhen you finish creating your project in your software, copy the share link or take a screenshot and publish it onto your student portfolio website!
Reflect
Learning check
Teacher setup, curriculum links and progress descriptors
Spark support
Routine: What If...?
Teacher notes: Facilitate the What If...? routine for 2โ3 minutes. Encourage students to connect the prompt to Perspective (Secure global communication relies on mathematical key pairs.).
Achievement pathway
- Foundation: States that websites use secret encryption to protect credit cards and passwords.
- Developing: Explains the problem with symmetric keys: if you send the secret key over the internet, someone could intercept it.
- Secure: Role-plays Public/Private key exchange using the 'Padlock & Box' analogy (Public key = open padlock everyone can lock; Private key = secret key only you hold).
- Mastering: Explains how HTTPS and SSL certificates use asymmetric encryption to establish secure internet connections.
Curriculum links
Curriculum strand: Everyday Digital Skills & Computational Science
Outcome: CY.02.B.1.2 โ Differentiate between single-key (symmetric) and dual-key (public/private key) encryption.
PYP: Perspective ยท Secure global communication relies on mathematical key pairs.
Learner profile: Open-minded
Competency tags
Gate support
Accessibility alternative: Students may verbally explain or point to the correct answer for "In Public-Key (Asymmetric) Encryption, which key must you NEVER share with anyone?" with a teacher or teaching assistant.
Teacher override: allow
Locked level
Level 5: One-Way Hashing & Data Integrity
Complete the previous learning check to unlock this next level.
One-Way Hashing & Data Integrity
Explain one-way cryptographic hash functions and their role in password storage and file integrity.
Learning objective
Students will demonstrate that a hash function creates a unique, fixed-length fingerprint that changes completely if even one character is altered.
Let's Go!
Learn
A Hash Function is like a digital blender! It takes any text or file and turns it into a unique string of characters (like `e3b0c442...`). It is a ONE-WAY process: you cannot reverse a hash back to the original text. Websites store password hashes so hackers can't read your real password!
Mathematical definition of the Caesar shift with alphabet wrap-around:
Expected distribution across 100,000 words in standard English corpora:
| Letter | Freq % | Letter | Freq % |
|---|---|---|---|
| E | 12.70% | T | 9.06% |
| A | 8.17% | O | 7.51% |
| I | 6.97% | N | 6.75% |
| S | 6.33% | H | 6.09% |
| R | 5.99% | D | 4.25% |
Mathematical foundation of public/private key trapdoor one-way functions:
Apply Simulator Skills โข Try it yourself
Test the Avalanche Effect
๐ Open a practice space
๐ Student Project GuideSuccess Criteria & WAGOLL (What A Good One Looks Like)
๐ฏ Task Success Criteria (Rubric)
Understands that websites store passwords in a scrambled form rather than plain text.
Observed that changing 1 letter in an input produces a completely different hash output (Avalanche Effect).
Explains why hashing is a 1-way function (easy to compute forward, impossible to reverse back into the password).
Demonstrates how file checksums (hashes) verify if a downloaded file has been tampered with or corrupted.
๐ What A Good One Looks Like (WAGOLL)
โญ Mastering StandardWhen you finish creating your project in your software, copy the share link or take a screenshot and publish it onto your student portfolio website!
Reflect
Learning check
Teacher setup, curriculum links and progress descriptors
Spark support
Routine: See, Think, Wonder
Teacher notes: Facilitate the See, Think, Wonder routine for 2โ3 minutes. Encourage students to connect the prompt to Change (Irreversible digital signatures guarantee data authenticity and security.).
Achievement pathway
- Foundation: Understands that websites store passwords in a scrambled form rather than plain text.
- Developing: Observed that changing 1 letter in an input produces a completely different hash output (Avalanche Effect).
- Secure: Explains why hashing is a 1-way function (easy to compute forward, impossible to reverse back into the password).
- Mastering: Demonstrates how file checksums (hashes) verify if a downloaded file has been tampered with or corrupted.
Curriculum links
Curriculum strand: Everyday Digital Skills & Computational Science
Outcome: CY.03.B.1.1 โ Explain one-way cryptographic hash functions and their role in password storage and file integrity.
PYP: Change ยท Irreversible digital signatures guarantee data authenticity and security.
Learner profile: Principled
Competency tags
Gate support
Accessibility alternative: Students may verbally explain or point to the correct answer for "What makes a cryptographic hash function different from normal encryption?" with a teacher or teaching assistant.
Teacher override: allow
Locked level
Level 6: Cybersecurity & Ciphers Audit
Complete the previous learning check to unlock this next level.
Cybersecurity & Ciphers Audit
Evaluate real-world cryptographic applications (HTTPS, Wifi WPA3, Blockchain) and design a secure communication system.
Learning objective
Students will audit a simulated school network connection, identifying where encryption (HTTPS/WPA3) protects data in transit.
Let's Go!
Learn
Encryption is the invisible shield of the internet! Every time you see `https://` and a padlock in your browser, your connection is using SSL/TLS encryption. Without cryptography, online banking, private messaging, and secure voting would be impossible. In computing, robust security infrastructure protects human privacy and global systems. As you explore the interactive Cipher Wheel Simulator below, focus on how to construct a full security diagram mapping how data moves from user device -> Wi-Fi encryption -> HTTPS web server.
Mathematical definition of the Caesar shift with alphabet wrap-around:
Expected distribution across 100,000 words in standard English corpora:
| Letter | Freq % | Letter | Freq % |
|---|---|---|---|
| E | 12.70% | T | 9.06% |
| A | 8.17% | O | 7.51% |
| I | 6.97% | N | 6.75% |
| S | 6.33% | H | 6.09% |
| R | 5.99% | D | 4.25% |
Mathematical foundation of public/private key trapdoor one-way functions:
Apply Simulator Skills โข Try it yourself
School Network Security Audit
๐ Open a practice space
๐ Student Project GuideSuccess Criteria & WAGOLL (What A Good One Looks Like)
๐ฏ Task Success Criteria (Rubric)
Locates the padlock icon in a browser address bar indicating HTTPS encryption.
Explains the risk of sending unencrypted data over public open Wi-Fi networks.
Constructs a full security diagram mapping how data moves from user device -> Wi-Fi encryption -> HTTPS web server.
Evaluates emerging cryptographic concepts (Quantum computing threats to encryption) and presents a security recommendation report.
๐ What A Good One Looks Like (WAGOLL)
โญ Mastering StandardWhen you finish creating your project in your software, copy the share link or take a screenshot and publish it onto your student portfolio website!
Reflect
Learning check
Teacher setup, curriculum links and progress descriptors
Spark support
Routine: 3-2-1 Bridge
Teacher notes: Facilitate the 3-2-1 Bridge routine for 2โ3 minutes. Encourage students to connect the prompt to Responsibility (Robust security infrastructure protects human privacy and global systems.).
Achievement pathway
- Foundation: Locates the padlock icon in a browser address bar indicating HTTPS encryption.
- Developing: Explains the risk of sending unencrypted data over public open Wi-Fi networks.
- Secure: Constructs a full security diagram mapping how data moves from user device -> Wi-Fi encryption -> HTTPS web server.
- Mastering: Evaluates emerging cryptographic concepts (Quantum computing threats to encryption) and presents a security recommendation report.
Curriculum links
Curriculum strand: Everyday Digital Skills & Computational Science
Outcome: CY.03.B.1.2 โ Evaluate real-world cryptographic applications (HTTPS, Wifi WPA3, Blockchain) and design a secure communication system.
PYP: Responsibility ยท Robust security infrastructure protects human privacy and global systems.
Learner profile: Reflective
Competency tags
Gate support
Accessibility alternative: Students may verbally explain or point to the correct answer for "What does the padlock icon next to a web address (HTTPS) tell you?" with a teacher or teaching assistant.
Teacher override: allow


