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Chapter 8
Variables

Level: Newbie

Sometimes, it’s necessary to draw a figure on a different scale. For example, if we want to draw a square with side length 100, a square with side length 200 and a square with side length 50, we need actually three different procedures for each square.

to square1  
repeat 4 [forward 100 right 90]  
end  
to square2  
repeat 4 [forward 200 right 90]  
end  
to square3  
repeat 4 [forward 50 right 90]  
end

We can see immediately that it would be easier to define a single procedure waiting for an argument: the side length. For example, square 200 should draw a square with side length 200, square 100 should draw a square with side length 100 ... It’s time to introduce the variable notion!

 8.1 Examples
 8.2 Drawing a rectangle with chosen dimension
 8.3 Drawing at different scales
 8.4 Exercice:

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