Instructor Notes — Week 8

Theme: Radio, Waves, Communication
Focus Concept: Wireless communication using the micro:bit radio
Mini‑Project: Pass the Ghost — broadcasting, receiving, and relaying messages

Learning Objectives

  • Understand the idea of radio waves as part of the electromagnetic spectrum
  • Describe how micro:bits send and receive data using radio groups
  • Read and write TTC‑style pseudocode involving events, conditions, and loops
  • Build a simple communication game using broadcasting
  • Reason about randomness, IDs, and message routing

Vocabulary Focus

  • radio – wireless communication using invisible waves
  • broadcast – sending a message to everyone listening
  • ID – a number that identifies each participant
  • condition – a yes/no check the program uses
  • event – something that triggers code (shake, receiving a number)
  • random number – an unpredictable value chosen by the computer

Part A — Science Warm‑Up: Waves, Sound, and Radio

(Use your own explanations from the session — this simply structures them for notes.)

What we covered:

  • Sound waves: vibrations travelling through air
  • Light waves: part of the electromagnetic spectrum
  • Radio waves: invisible light used for communication
  • Why radios don’t need wires
  • Why we use channels (micro:bit “groups”) to avoid interference

Explain to participants:

“When a micro:bit sends a radio message, it’s like shouting — anyone on the same channel can hear it.
When it listens, it’s like keeping its ears open for incoming messages.”

This sets the foundation for Part B.

Part B — Project: Pass the Ghost

Below is the full TTC‑style breakdown of the game you built.

Blocks version:

B1 — Full TTC‑Style Pseudocode

WHEN program starts DO
    SET radio group TO 1
    SET radio power TO highest
    SET ID TO a chosen number
    SET players TO total number of players
    SET ghost TO false

    IF ID = 1 THEN
        SHOW ghost icon
        SET ghost TO true
    END IF
END WHEN

WHEN a radio number is received DO
    IF received number = ID THEN
        SET ghost TO true
        SHOW ghost icon
    END IF
END WHEN

WHEN device is shaken DO
    IF ghost = true THEN
        SET target TO ID
        WHILE target = ID DO
            SET target TO [random number from 1 to players]
            PAUSE 10 ms
        END WHILE
        SET ghost TO false
        SEND radio number target
        CLEAR screen
    END IF
END WHEN

B2 — Step‑by‑Step Build With Explanations

Below each step is a detailed explanation you can use when teaching.

Step 1 — Radio Setup

SET radio group TO 1
SET radio power TO highest
SET ID TO a chosen number
SET players TO total number of players
SET ghost TO false

Explanation

  • A radio group is like a walkie‑talkie channel
  • All micro:bits on the same group can hear each other
  • Each participant gets an ID (1–10 in your version)
  • ghost starts as false because only Player 1 begins as the ghost

Ask participants:

“Why can’t everyone be on different groups?”
“Why do we need an ID?”

Step 2 — Start With One Ghost

IF ID = 1 THEN
    SHOW ghost icon
    SET ghost TO true
END IF

Explanation

  • Only player 1 starts as the ghost
  • Showing the ghost icon gives visual feedback
  • ghost = true means “I am currently the ghost”

Useful question:

“Why do we only let one player start as the ghost?”

Step 3 — Receiving a Message

WHEN a radio number is received DO
    IF received number = ID THEN
        SET ghost TO true
        SHOW ghost icon
    END IF
END WHEN

Explanation

  • When someone broadcasts a number, everyone hears it
  • Each micro:bit checks: Is the message meant for me?
  • If yes → that player becomes the ghost
  • If not → ignore it

Analogy:

“This is like shouting a name in a playground — only the person whose name you said reacts.”

Step 4 — Shake to Pass the Ghost

WHEN device is shaken DO
    IF ghost = true THEN
        SET target TO ID
        WHILE target = ID DO
            SET target TO [random number from 1 to players]
            PAUSE 10 ms
        END WHILE
        SET ghost TO false
        SEND radio number target
        CLEAR screen
    END IF
END WHEN

Explanation

This is where most of the logic happens.

Break it down clearly:

A. Only the ghost can pass the ghost

IF ghost = true THEN

Everyone else shaking their micro:bit does nothing.

B. Pick a target

SET target TO ID
WHILE target = ID DO
    SET target TO [random number from 1 to players]
END WHILE
  • Start by setting target to your own ID
  • Keep picking random players until you get a number that is not yours
  • This prevents passing the ghost to yourself

Ask:

“What would happen if we didn’t use the WHILE loop?”

C. Send the message

SET ghost TO false
SEND radio number target
CLEAR screen
  • You are no longer the ghost
  • The chosen player will receive the message
  • Clearing the screen removes the ghost icon

B3 — Final Program Behaviour (Summary)

  • Exactly one person starts as the ghost
  • Shaking sends the ghost to someone else
  • Radio messages carry the ID of the next ghost
  • No wires — everything is wireless
  • Program combines events, loops, conditions, randomness, and radio

Reflection & Wrap‑Up

You can finish the session by asking:

  • “How does the micro:bit know who the message is for?”
  • “Why do we use random numbers?”
  • “How is sending a radio message like sending a text message?”
  • “Where do we check if we are the ghost?”
  • “Why do we need the WHILE loop?”

Tie it back to real-world communication:

  • Wi‑Fi
  • Bluetooth
  • Mobile phones
  • Spacecraft sending signals