Code Rock Paper Scissors on a micro:bit with EduBlocks

Overview

In this project you will learn how to code your to play rock, paper, scissors using gestures and the . We will start by understanding the basic game logic and how to present rock, paper, and scissors on the LED matrix. You will discover how to use selection for the micro:bit's choice and show it on the LED matrix, so players can see what the micro:bit picked and work out whether they have won. Through this project you will develop fundamental coding concepts like , conditionals and random numbers while creating something fun and interactive. By the end you will have a fully functional game that you can play with friends or challenge the micro:bit yourself.

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What you'll learn

What you'll need

The micro:bit EduBlocks editor
micro:bit
micro USB cable
battery pack for the micro:bit (optional)

Key words

Importing Libraries

A library is a ready-made bundle of code that someone else has written for you. Importing a library means bringing it into your project so you can use all its ready-made commands and features, without building them from scratch.

Real-world example: It's like borrowing a recipe book from the library. Instead of working out every recipe yourself, you bring the book in and use the recipes whenever you need them.

Variable

A variable is something that can change. Think of it like a labelled box: you pop something inside, and the label tells you what it is. You can swap what's inside whenever you like.

Real-world example: A variable called score might start at 0, then change to 1, 2 and 3 as you collect points in a game.

While loop

A while loop keeps repeating its instructions for as long as something stays true. The moment that thing stops being true, the loop stops.

Real-world example: "While it's still raining, keep the umbrella up." As soon as the rain stops, you put the umbrella down, and the loop ends.

If statement

An if statement checks whether something is true, and only runs its instructions when it is. It's how code makes decisions.

Real-world example: "If it's cold, put on a coat." If it's warm, you skip the coat, the action only happens when the check is true.

Accelerometer

An accelerometer is a tiny part inside the micro:bit that senses movement, like tilting, shaking or being turned over. It turns that movement into numbers your code can react to.

Real-world example: A bit like the sensor in a games controller that knows when you tilt it to steer, the accelerometer notices when the micro:bit moves.

LED Matrix

The LED matrix is the grid of little red lights on the front of the micro:bit. By switching them on and off in patterns, your code can show numbers, letters and tiny pictures.

Real-world example: Like a mini scoreboard made of dots, the LED matrix lights up to spell out your step count.

Comparison Operators

A comparison operator checks how two things measure up, for example whether they are equal or one is bigger than the other. It gives back a simple true or false answer.

Real-world example: Asking "is 6 == 6?" gives back true, but "is 6 == 2?" gives back false, so your code knows whether the two numbers match.

Random

Random means you can't guess what's coming next, a bit like rolling a dice. The computer picks for you, so you get a different surprise each time.

Real-world example: Asking a computer for a random number between 1 and 6 is just like rolling a dice, you never know if you'll get a 1 or a 6.

Set up your micro:bit EduBlocks Editor

Open your web browser. We recommend Google Chrome or Microsoft Edge.
In the address bar type app.edublocks.org.
Under Create New Project, select micro:bit. Name your project Rock Paper Scissors, and make sure block is selected under type.

Creating a new EduBlocks project

Select Create to open the micro:bit editor.

The EduBlocks code area

Importing MicroPython libraries

Select Basic, select Imports. Select from microbit import * and snap it to the # Start code here block.
Select Basic, select Imports, select an import random block and snap it to the from microbit import * block.

This that we need to create our game.

Importing the MicroPython libraries

Create a While Loop

Select Basic, select Loops. Select a while True: block and snap it to the import random block.

This creates a loop that goes around and around forever.

Creating a while loop

Create the Paper Variable

Select Variables. Select Create Variable and name it paper.
Select a paper = 0 block and snap it within the while True block.
Select Display. Select an Image block and snap it onto the paper = block where it says 0.
Create the following pattern within the Image block. A 9 means the LED is turned on and a 0 means the LED is off.

Creating a representation of paper in lights

Here is the code so far:

Image of completed code so far

Create the Rock Variable

Select Variables. Select Create variable and name it rock.
Select a rock = 0 block and snap it below the paper = Image ("99999:", "90009:", "90009:", "90009:", "99999") block.
Select Display. Select an Image block and snap it onto the rock = block where it says 0.
Create the following pattern within the Image block.

Representation of rock in code

Completed code so far:

Completed code so far.

Create the Scissors Variable

Select Variables. Select Create Variable and name it scissors.
Select a scissors = 0 block and snap it below the rock = Image ("00000:", "09990:", "09990:", "09990:", "00000") block.
Select Display. Select an Image block and snap it onto the scissors = block where it says 0.
Create the following pattern within the Image block.

Representation of Scissors in code

Completed code so far with the scissors variable added.

Completed code so far

Check for a Shake

Select Basic, select Logic, select an if True: block and snap it to the scissors = Image ("90099:", "09099:", "00900:", "09099:", "90099") block.
Select Accelerometer. Select an accelerometer.was_gesture ("shake") block and snap it onto the if block where it says True.
Select Variables, select Create Variable and name it choice. Select a choice = 0 block and snap it inside the if accelerometer.was_gesture ("shake"): block.
Within the 0 of the choice block type random.randint(0, 2)

This will check to see if the micro:bit has been shaken and if it had it will set choice to a random number between 0 and 2.

Checking to see if the micro:bit has been shaken

Create the If Condition

Select Basic, select Logic, select an if True: block and snap it to the choice = random.randint(0, 2) block.
Select Basic, select Logic, select a 0 == 0 block and snap it on to the if block where it says True.
Select Variables. Select a choice block and snap it onto the if block before the == sign.
Select Display. Select a display.show(10) block and snap it inside the if choice == 0: block.
Select Variables. Select a paper block and snap it onto the display.show block where it says 10.

This will check to see if choice is equal to 0 and if it is paper will be displayed on the LED matrix.

Creating the if condition

Create the elif Condition

Select Basic, select Logic. Select an elif True: block and snap it to the if choice == 0: block.
Select Basic, select Logic. Select a 0 == 0 block and snap it onto the elif block where it says True. Change the 0 to 1.
Select Display. Select a display.show(10) block and snap it into the elif choice == 1: block.
Select Variables. Select a rock block and snap it onto the display.show block where it says 10.

This will check to see if choice is equal to 1 and if it is rock will be displayed on the LED matrix.

Creating the elif condition

Create the Else Condition

Select Basic, select Logic. Select an else: block and snap it to the elif choice == 1: block.
Select Display. Select a display.show(10) block and snap it inside the else: block.
Select Variables. Select a scissors block and snap it onto the display.show block where it says 10.

This will display scissors on the LED matrix if choice does not equal 0 or 1.

Creating the else condition

Downloading the Code

Connect the micro:bit to the computer with the micro USB cable.
Select Connect and follow the on-screen prompts to pair the micro:bit with your web browser.
Select Download to send the code to your micro:bit.

Run it and Watch

In the web browser

EduBlocks has a built-in micro:bit simulator, handy if you haven't got a micro:bit to hand.

On the right-hand side of the screen, select Simulator.
From the accelerometer menu below the simulator, select Shake.
Select Send. This simulates a shake of the micro:bit and you will see a rock, paper, or scissors icon display on the LED matrix.

The EduBlocks simulator

On a real micro:bit

Once the code has downloaded, give the micro:bit a shake and see an icon display on the LED matrix. Why not find a friend and see who can beat the micro:bit?

Try it yourself

Challenge: Can you add a sound so your micro:bit gives a little beep each time it makes a choice? Try snapping an audio.play(Sound.HAPPY) block from Audio inside your if accelerometer.was_gesture("shake"): check, just after you set the choice. For an extra challenge, pick a different sound for rock, paper and scissors!

Good to know: the sound plays through the built-in speaker, which only the micro:bit V2 has. If you have a V1, you can still try this challenge by clipping a buzzer or headphones to the pins. Everything else in this project works happily on both V1 and V2.

Stuck? Quick fixes

Problem	Try this
Nothing happens when I shake it	Give it a firm shake, not too gentle. Also check your blocks are snapped inside the `if accelerometer.was_gesture("shake"):` block.
The same icon keeps showing	That's normal! The choice is random, so shake a few more times and the others will appear.
My icons look wrong or blank	Open each Image block and check you've selected the right squares for rock, paper and scissors.
It only ever shows two icons	Check your elif is set to choice == 1, and that random.randint goes from 0 to 2.
It won't download to my micro:bit	Make sure the micro:bit is plugged in with the USB cable, then try Connect again.