Instructor Notes — Week 7

Theme: Functions and Game Mechanics
Focus Concept: Breaking programs into reusable pieces (functions) and combining multiple systems (movement, collisions, timing)
Mini‑Projects:

Part A: Understanding and using functions
Part B: Building a simplified Space Invaders game

Learning Objectives

By the end of this session, participants should be able to:

Read and explain TTC‑style pseudocode for functions and game logic.
Define and call functions with and without parameters.
Recognise when a function is useful for reusing repeated logic.
Understand how sprites move, detect collisions, and interact in real time.
Apply loops, conditions, variables, and timing together in a multi‑step game.

Vocabulary Focus

function – a reusable block of instructions that can be called from different places.
parameter – a value you give a function so it can work in a flexible way.
return value – what a function sends back to you when it finishes.
event – something the micro:bit reacts to (button press, interval).
sprite – a moving object on the LED grid.
collision – when two sprites touch.
logic – the set of rules a program follows when deciding what to do.

Use model sentences like:

“This function needs a parameter to decide how long to pause.”
“The sprite moves up by changing its y‑position.”
“A collision happens when the laser touches the alien.”

Part A — Functions (Understanding, Predicting, Building)

In this part, participants learn what functions are, why we use them, and how to build them.
We introduce three example functions:

flashHeart() – no parameters
flashSquare(time) – takes a parameter
addNumbers(a, b) – takes parameters and returns a value

Blocks version (MakeCode)

A1 — TTC Pseudocode: Function Definitions

`flashHeart`

DEFINE FUNCTION flash_heart
    SHOW ICON heart
    PAUSE 200 ms
    SHOW ICON small_heart
    PAUSE 200 ms
END FUNCTION

`flashSquare`

DEFINE FUNCTION flash_square WITH parameter time
    SHOW ICON square
    PAUSE time
    SHOW ICON small_square
    PAUSE time
END FUNCTION

`addNumbers`

DEFINE FUNCTION add_numbers WITH parameters a, b
    RETURN a + b
END FUNCTION

A2 — Event Handlers Calling Functions

WHEN button A is pressed DO
    CALL flash_square WITH 300
END WHEN

WHEN button AB is pressed DO
    CALL flash_square WITH add_numbers(600, 400)
END WHEN

WHEN button B is pressed DO
    SHOW NUMBER add_numbers(33, 34)
END WHEN

CALL flash_heart

A3 — Instructor Explanation (Verbose)

What is a function?

A function is like a reusable “recipe”. Instead of writing the same code over and over, you write it once, give it a name, and call it whenever you need it.

Explain using real life examples:

“Tying shoelaces” is a function.
“Making a sandwich” is a function.
“Showing a flashing heart” is a function.

Why do we use parameters?

Parameters make a function adjustable.
flashSquare(time) becomes more powerful because the pause length can change.

What is a return value?

Some functions give back a result.
Participants should understand this like a vending machine: you give input → you get output.

Analysing each function

flash_heart – always the same effect, no parameters.
flash_square(time) – customisable; the time makes the square flash faster or slower.
add_numbers(a, b) – invisible on the LEDs, but useful for calculations.

Linking to events

Button A → fixed timing flash
Button AB → flash using calculation
Button B → shows a number from a function
Finally flash_heart runs automatically on startup

Key teaching point

“Functions help keep your code short, clean, and powerful.”

Part B — Space Invaders Game Build

The second half of Week 7 uses everything learned so far:

functions (optional extensions)
loops
conditions
collisions
sprite movement
timing

This project is split into clear steps so participants understand each mechanic.

Blocks version (MakeCode)

Part B1 — Setting Up the Sprites

TTC Pseudocode

SET Alien TO NEW SPRITE AT (0, 0)
SET Ship TO NEW SPRITE AT (2, 4)