Variables

The idea

Think of a variable like a labeled jar that remembers how many marbles are inside it - 'set to 0' empties the jar and starts over, 'change by 1' drops one more marble in without touching the ones already there.

What it actually is

A Variable is a named box that remembers a value - like a score - across the whole time a project runs. 'Make a Variable' creates one, 'set [variable] to (0)' gives it a starting value, and 'change [variable] by (1)' adds to whatever it currently holds.

How you write it

set [score] to (0)
change [score] by (1)

A worked example

when 🏳️ clicked
set [score] to 0

when this sprite clicked
change [score] by 1
say (join "Score: " (score)) for 1 seconds

The green-flag script resets score to 0 at the very start. Every time the sprite is clicked, its own script adds 1 to score and shows the new total - the variable remembers its value across every single click, not just the current one.

Mistakes children actually make

Mistake 1: forgetting to 'set' a variable to a starting value when the project begins - without a reset, a score can start at whatever it was left at from the LAST time the project ran. Mistake 2: mixing up 'set' (replaces the value completely) and 'change by' (adds to whatever's already there) - using 'set 1' repeatedly never actually adds up.

Then they try it

In the app this lesson continues with the animated explanation, spoken aloud, and then the practice: Make a variable, set it to a starting value, and change it by some amount. The editor runs your child’s real code and checks the result, with their coding buddy reacting to what they wrote.