Rock, paper, scissors

Step 1: Make it

What is it?

Play this classic game with two micro:bits and learn about selection, variables and random numbers at the same time.

These two videos show you what you'll make and how to code it:

How it works

• Rock, paper, scissors is a classic game of chance for two people. You and a partner shake your fists 3 times and then make gestures at random to show a rock, paper or scissors. Rock beats scissors, scissors beat paper and paper beats rock (it wraps the rock!).
• When the micro:bit accelerometer detects a shake movement, it sets the variable tool to a random number: 0, 1 or 2.
• We use 0 because computers start counting at 0, and it’s good to remember that 0 is a number!
• The program uses selection to decide what image to show on the LED display. If the random number was 0, it shows a rock icon, if it was 1 it shows the icon representing paper. If it wasn’t 0 or 1, it must be 2 because we instructed the micro:bit to only pick random numbers between 0 and 2, so in that case it shows scissors.

What you need

• 2 micro:bits (or MakeCode simulator)
• MakeCode or Python editor
• battery packs (optional)
• a partner to play with

Step 2: Code it

1from microbit import *
2import random
3
4while True:
5    if accelerometer.was_gesture('shake'):
6        tool = random.randint(0,2)
7        if tool == 0:
8            display.show(Image.SQUARE_SMALL)
9        elif tool == 1:
10            display.show(Image.SQUARE)
11        else:
12            display.show(Image.SCISSORS)

Step 3: Improve it

• Draw your own icons for rock, paper, scissors.
• Think of other tools that could replace rock, paper and scissors or invent new rules.
• Use the micro:bit radio function to make a game that knows if you won or lost by communicating with your friend’s micro:bit.