Operation Manual

A beginner’s guide to Scratch
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Now, let’s build our script. Before you start, select the “lights” sprite in the
Sprites List.
First things first: we want to start with the lights out. So we use a green flag event
to switch our lights sprite to “costume1”, which shows three black lights.
As the train approaches the level crossing barrier, I have used an “when [ ] key
pressed” block from Control to detect it, setting the value to “t”. This event will
trigger the lights, alarm and barrier. But first, let’s deal with the alarm.
Build the script you can see in the screenshot above. This will cause the alarm to
sound when the “t” key is pressed.
Notes:
Import your sound effect
from the Sounds tab. You’ll
find it right next to the
Scripts and Costumes tabs.