Operation Manual

A beginner’s guide to Scratch

Have a look at the screenshot above. We have used the “when [space] key

pressed” event from Control to run the program. The robot sprite is moved to the

centre of the screen using a “go to x: [0] y: [0]” block from Motion (see “Positioning

your sprite”, in Lesson 1.3).

The rest of the code is placed inside a “repeat until” loop (from Control). Inside the

repeat loop, we have an “if” (a conditional statement) that checks if the “up arrow”

key has been pressed. This has been set to a “key [up arrow] pressed” event

(from Sensing).

The “touching [ ]?” block from Sensing is set to “edge”. That means that if the

robot touches the edge of the Scratch screen, the event will stop the script.

An “event” is something that happens in a program.

In this script, there are two possible situations:

1. The “up arrow” key has been pressed – in which case, the robot will walk up the

screen for 20 steps, switching costumes as it does so.

2. The “up arrow” key has not been pressed – in which case, the robot will

do nothing.

That’s not going to be very useful. Let’s see if we can do better.

To see an example of this script, open RPiScratch/Projects/robot_v1.

This script will

make our robot

move on our

command, but

only in one

direction.

Notes: