First forward into Logo 6: variables and procedures

Learn to write procedures and build them into Logo programs. Learn to use variables.

Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
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Problem

First Forward Into Logo

Previous: FF5

 

In FF4 you investigated the instruction:

REPEAT 360 [FD 1 RT 1]

Hopefully you altered it as you saw fit and produced some exciting shapes. So it is timely to introduce you to the idea of a variable . As the word implies, a variable is something that varies, something that changes.

You may find the following a quicker way of drawing circles and circular patterns. It is called a procedure and has to be written in a particular way.

TO CIRCLE :CH

REPEAT 360 [ FD :CH RT 1]

END

Notice how the procedure is set out:

First a title / a command TO CIRCLE

then the variable :CH

followed by the instructions REPEAT 360 [ FD :CH RT 1]

then a formal closing of the procedure END

N.B. the variable, :CH could have been any letter or letters that you wish!

 



 

Now experiment with the procedure:



 

CIRCLE 3
CIRCLE 6
CIRCLE -3
CIRCLE 9
Image
First Forward into Logo 6: Variables and Procedures



 

Building on this idea of a procedure we could have written:

TO CIRC :CH :ANG

REPEAT 360 [ FD :CH RT :ANG]

END

This is a procedure with two variables!

Can you anticipate what will change and what will happen now?

Can you see what is now possible?

Go on experiment! Try:

CIRC 3 3

CIRC 3 6

CIRC 3 30

What is happening?

Why not be bolder and try say:
CIRC 30 90
CIRC 30 45
CIRC 30 18 etc., etc.,
Image
First Forward into Logo 6: Variables and Procedures



 

What do you notice?

What conclusions can you come to?

 

 

Next: FF7