Grade 3 Coding and Robotics: Encoding & Decoding Messages – Week 2 Term 4

1. Encode

To change a message into a secret code using letters, numbers, or symbols so others cannot easily read it

2. Decode

To change a secret code back into the original message so it can be read and understood

3. Cipher

A secret way of writing messages using a special pattern or rule (like A=1, B=2, C=3)

4. Algorithm

A step-by-step set of instructions to solve a problem or complete a task, like a recipe

5. Pattern

A repeated design or sequence that follows a rule, which can be used to predict what comes next

Hook Activity: The Secret Spy Mission

Welcome learners as “Junior Coding Spies” who need to learn secret code skills! Show them a mysterious envelope containing an encoded message: “8-5-12-12-15 3-15-4-5-18-19” (HELLO CODERS). Ask: “Can anyone crack this secret code?” Build excitement about learning to decode messages like real computer programmers!

Introduction Activities:

• Quick Review Game (5 mins): Play “Alphabet Number Race” – call out letters and learners shout their number position (A=1, B=2, etc.). This activates prior knowledge and reinforces the cipher pattern.
• Real-World Connection (5 mins): Discuss where we use codes in real life: passwords for games, QR codes, barcodes on products, secret messages between friends. Explain that computers use codes (like binary) to store all information!
• Learning Objectives Share (3 mins): Display today’s objectives using the “Secret Mission Board” – learners will become expert encoders and decoders by the end of the lesson.
• Vocabulary Introduction (7 mins): Introduce the 5 key words using visual aids and simple definitions. Create a “Code Breaker’s Dictionary” poster that stays up throughout the lesson.

Direct Instruction (20 minutes):

Step 1: Modeling Encoding (10 mins)

• Display the alphabet-number cipher chart clearly
• Model encoding a simple word on the board: “CAT” → “3-1-20”
• Think aloud through the process: “C is the 3rd letter, so it becomes 3. A is the 1st letter, so it becomes 1…”
• Model encoding a full sentence: “I LIKE CODING” → “9 12-9-11-5 3-15-4-9-14-7”
• Emphasize the algorithm: 1) Look at letter, 2) Find position in alphabet, 3) Write the number, 4) Add dash or space

Step 2: Modeling Decoding (10 mins)

• Show encoded message: “13-1-20-8 9-19 6-21-14”
• Model the reverse algorithm: 1) Look at number, 2) Find that position letter, 3) Write the letter
• Decode together: “MATH IS FUN”
• Show common mistakes to avoid: confusing similar numbers (1 and 11), forgetting spaces between words
• Introduce simple symbols as word shortcuts: ☀️ for space, ❤️ for “the”, ⭐ for “is”

Guided Practice (30 minutes):

Activity 1: Decode the Mystery Messages (15 mins)

• Distribute worksheets with 3 encoded messages (increasing difficulty)
• Message 1 (Easy): “23-5 12-15-22-5 3-15-4-9-14-7” (WE LOVE CODING) – 2 words
• Message 2 (Medium): “8-5-12-12-15 ❤️ 23-15-18-12-4” (HELLO THE WORLD) – using one symbol
• Message 3 (CAPS Standard): Create a 7-word sentence for learners to decode
• Circulate to provide support, asking guiding questions: “What position is that letter in the alphabet?”
• Have fast finishers check their answers with a partner

Activity 2: Encode Your Own Message (15 mins)

• Learners work in pairs to encode a sentence about something they enjoy
• Requirement: Must be 7 words long (CAPS standard)
• Example: “I enjoy playing soccer with my best friends”
• Encourage use of at least one symbol from the symbol chart
• Pairs swap messages with another pair to decode
• Pairs verify if their message was decoded correctly – practicing debugging!

Independent Practice (30 minutes):

Activity 3: Secret Message Treasure Hunt (20 mins)

• Set up 5 stations around the classroom with encoded clues
• Each clue reveals the location of the next clue when decoded
• Final clue leads to “treasure” (certificate, sticker, or small reward)
• Learners work individually or in small groups (max 3)
• Each clue is a 7-word sentence (meeting CAPS requirements)
• Example Clue 1: “14-5-24-20 3-12-21-5 ⭐ 14-5-1-18 ❤️ 4-15-15-18” (NEXT CLUE IS NEAR THE DOOR)
• Teacher observes and notes learners’ problem-solving strategies

Activity 4: Create Your Own Cipher (10 mins)

• Challenge: Can learners create a NEW pattern for encoding?
• Examples: Reverse alphabet (A=26, Z=1), skip counting (A=2, B=4, C=6), or shape patterns
• Learners encode one sentence using their new cipher
• Include the “cipher key” so others can decode it
• This extends algorithmic thinking – creating their own rules/patterns!

Consolidation Activity (12 minutes):

Whole Class Reflection Circle

• Gather learners in a circle for discussion
• Ask: “Why do we need to encode messages?” (security, privacy, data transmission)
• Discuss: “How is what we did today similar to what computers do?” (computers encode everything – text, pictures, videos – into numbers called binary code!)
• Share: Have 3-4 learners share their favorite encoded message or their own cipher creation
• Emphasize the connection to algorithmic thinking: “You followed steps to solve problems – that’s what programmers do!”

Exit Ticket (8 minutes):

Quick Assessment Task

Each learner completes an exit slip with:

• Task 1: Encode their own name using the number cipher
• Task 2: Decode this message: “9 ❤️ 3-15-4-9-14-7” (I THE CODING – intentional error for debugging)
• Task 3: Draw one emoji/symbol to show how they feel about today’s lesson

Collect exit tickets to assess understanding and inform next lesson planning.

📝 Formative Assessment

• Observation during guided practice: Note which learners struggle with the cipher chart, have difficulty with letter-number correspondence, or make systematic errors
• Pair work monitoring: Listen to conversations – are learners explaining their thinking? Using vocabulary correctly?
• Treasure hunt participation: Track which learners complete independently vs. need support
• Exit ticket analysis: Quick check of encoding/decoding accuracy and debugging ability
• Questioning during lesson: “How did you figure that out?” “What pattern did you notice?” “What would you do if you got stuck?”

📋 Summative Assessment

• Encoded/decoded worksheet completion: Minimum 80% accuracy on standard 7-word sentences
• Independent cipher creation: Can learners create and apply a new encoding pattern?
• Peer teaching moments: Can learners explain the process to a classmate?
• Portfolio piece: Keep best encoded/decoded message as evidence of learning

🤝 For learners who need support:

• Provide a numbered alphabet chart that they can keep at their desk
• Start with 3-4 word sentences before moving to 7 words
• Use color-coding: vowels in one color, consonants in another
• Pair with a buddy for treasure hunt activity
• Pre-teach vocabulary in a small group before the main lesson
• Allow use of manipulatives (alphabet blocks, number cards) for hands-on encoding
• Provide partially completed worksheets with some numbers already filled in
• Offer extra processing time and verbal explanations

🚀 For advanced learners:

• Challenge them to create multi-layered codes (encode, then encode again!)
• Introduce Caesar cipher (shift alphabet by 3: A→D, B→E, C→F)
• Have them encode full paragraphs (10-15 words) instead of single sentences
• Create their own treasure hunt with encoded clues for classmates
• Research and present other types of ciphers (Morse code, Pigpen cipher)
• Use Scratch Jr to program a simple encoding “machine”
• Encode messages using both letters AND numbers in the same word
• Act as “code-breaking consultants” to help struggling learners

♿ For learners with barriers to learning:

• Visual impairments: Provide large-print cipher charts, use tactile letters and numbers, verbally describe all visual elements
• Hearing impairments: Use visual demonstrations, written instructions, ensure face-to-face communication
• Dyslexia/reading difficulties: Use dyslexia-friendly fonts, provide audio support, allow verbal responses instead of written
• ADHD: Break activities into smaller chunks, provide movement breaks, use timer for focus intervals
• Language barriers: Use Home Language examples, picture supports, peer support in Home Language
• Fine motor challenges: Allow typing instead of writing, use larger writing spaces, provide grip supports for pencils

✅ What worked well:

[To be completed after lesson – Consider: Which activities had highest engagement? Did learners grasp the encoding/decoding concept? Was the treasure hunt effective? Did timing work well?]

🔧 What could be improved:

[To be completed after lesson – Consider: Did any activities need more/less time? Were instructions clear enough? Which learners need additional support? Were differentiation strategies sufficient?]

📝 Notes for next lesson:

[To be completed after lesson – Consider: Which concepts need reinforcement? Ideas for follow-up activities? Assessment insights for planning? Links to upcoming robotics or algorithms lessons?]