MrW's Computing Blog

Recap

• What is a procedure?
• How do we code a procedure?
• What is a procedure with variables?

New skill

• random 100 = chooses a number between 1 and 50
• So typing “c random 100” draws a c which is between 1 and 100 big
• setpensize rnadom 30 chooses a pen width between 1 and 30
• If you c had two variables, then you could type:
  • c random 100 random 30
• The coordinates on the drawing canvas go from -250 to 250 across and -250 to 250 up and down.  (0,0) is in the middle.
• To make your shape appear in a random place:
  • setxy (-250 + random 500)  (-250 + random 500)

Tasks

1. Open you “c size procedure” file
2. Add the following code to make lots of random c shapes
   1. repeat 100
   2. [
   3. c random 100 random 30
   4. pu
   5. setxy  (-250 + random 500)  (-250 + random 500)
   6. pd
   7. ]
3. ** Put this line inside the repeat to get random colours!
   1. colour [random 255 random 255 random 255]
4. ** Write your own letter procedure with a variable :size instead of fd/bk numbers
5. *** Can you include a :col variable to choose the colour?
6. How else could you use random?  Try these ideas on different files
   1. circle random 100
   2. repeat 100 [fd random 100 rt 90]
   3. repeat 100 [fd random 200 setxy 0 0 rt 5]

See these posts for more ideas and techniques:

• Draw letter rainbows, flowers and shapes
• Stars and shapes 2
• Stars and shapes 1
• The power of procedures with variables
• Use variables to draw spirals
• Use variables to draw shapes
• Random
• Repeat, setxy, procedures

LOGO example files – can you work out how they work?

• Letter procedures
• Rectangle four variables
• Random colour wheel
• Spiral code
• Another spiral

A procedure is way of making a new command word in LOGO to do a specific task.

It’s a bit like a recipe for making a new meal.

In Year 4, we made a procedure to draw a letter c:

TO c

fd 20 rt 90 fd 20 bk 20 lt 90 bk 20 rt 90 fd 30 lt 90

END

Then we could just type c in our code when we wanted to draw a c.

Your task

1. Open this file and look through the code: Computing letters
2. Delete c o m p u t i n g
3. Code some other words using the letters of computing
4. Delete your word code (but keep all of the procedures)
5. Create your own letter procedure
   1. Decide on another letter, for example A
   2. Create the code to draw it
      1. make it the same size as the other letters
      2. include a “finger space” at the end of the letter
      3. make sure the arrow is facing up at the end
   3. When you are happy with your letter, put TO A (or whatever letter you did) and END around your letter code to make it into a procedure.
   4. Code a new word using the letters of computing and your letter
   5. ** Write a procedure for a second letter
   6. ** What’s the longest word you can code?
   7. *** Can you make your word into an arch?
      1. Before your first letter do   lt 30
      2. Between each letter turn right a bit
      3. Adjust the turns to get an even arch