MrW's Computing Blog

• Start a new project in LOGO
• Copy this code (copy and paste)

reset
setpensize 5

to rect :h :w :x :y
pu setxy :x :y pd
repeat 2 [fd :h rt 90 fd :w rt 90]
end

• Now you can draw any size rectangle anywhere on the page by typing:
  • rect 30 60 100 -50
• The first two numbers and the height and width
• The second two numbers are the x-coordinate and y-coordinate
  • The page goes from
    • -250 to 250 left to right
    • -250 to 250 bottom to top
• MAke a picture out of rectnangles
• ** Add a colour variable to the procedure
• ** Add another variable, eg
  • pensize
  • angle (dn’t forget to change the angle back again)
  • make it a parallelogram (one angle :ang, other angle (180 – :ang)  )

Khan academy drawing activity using JavaScript

Think of all the things you can draw in LOGO:

• Lines = fd 50 or bk 50
• Turns = rt 90 or lt 90 (or other angles)
• Circles = circle 50
• Squares = repeat 4 [fd 50 rt 90]
• Shapes =  repeat ? [fd 50 rt 360/?] (/ means divide; ? means number of sides)
• Stars = repeat ? [fd 50 rt 360 /? -180] same as shapes but change the angles; ? bigger than 8
• Spirals = see last post
• Colours = colour “blue
• Moving without drawing = pu setxy 100 100 pd
• Shading = fill (fills the area you are in with the current colour)
• Pen thickness = setpensize 5
• Procedures = to newthing …instructions… end
• Make/change  variables = make  “length 50
• Use variables = fd :length
• Increase variables = make “length :length + 1

Your task

• Design and draw a picture with different elements (could doa uick sketch in j2e5).
• Use as many skills from the list above as you can
• You can copy and paste code from your previous projects
• Lavel your code with comment lines starting with semi colon ; ,eg
  • ;———-Wheel———–

Ideas

• A car or vehicle
• A robot
• A house or building

You may copy and paste code from these instructions to save time typing.

Start a new LOGO file
Type:
    reset
    setpensize 5

Copy the following PROCEDURE:

    to snowflake
    repeat 6 [fd 20 bk 20 rt 60]
    end

Now whenever you want to draw a snowflake, you just have to write snowflake  rather than typing all of the code for a snowflake.  The code above is called a PREOCEDURE – it teaches the computer a new word and what it means.

Try this

    snowflake
    repeat 10 [snowflake fd 20 rt 36]

Why did we use the numbers 10 (for repeat) and 36 (for the right turn)?

You can also add a VARIABLE to a procedure.  Change the snowflake procedure to this:

    to snowflake :size
    repeat 6 [fd :size bk :size rt 60]
    end

Now when you call snowflake, you need to put a number with it, which will be how big it is.

Try this:

snowflake 50

snowflake 100

You can add other variables to the snowflake too.  Change the procedure to this:

to snowflake :size :col :pensize
   colour :col
   setpensize :pensize    
   repeat 6 [fd :size bk :size rt 60]
end

Then type for example:   snowflake 60 “blue 10

Let’s make a snowstorm…

Copy this code:

repeat 100
[
pu setxy (250 – random 500) (250 – random 500) pd
snowflake random 50 “blue random 15
]

Now tinker, play, experiment…

You could add this after the reset: colour “blue fill then make your snowflakes white

1. j2launch – 
2. Click on Level 3 
3. Type reset
4. This code draws a single step like the one below:
   • fd 30
   • rt 90
   • fd 30
   • lt 90
5. Press play – you should get this: 
6. Now add this to your code:
   • pu
     setxy -200 50
     pd
7. Challenge 1:  Make this shape by typing more instructions: 
8. Now add this to your code:
   • pu
     setxy 130 100
     pd
9. Challenge 2: Now make a square:  
10. Now add this to your code:
    • pu
      setxy -140 -140
      pd
11. Challenge 3:  
12. Now add this to your code:
    • pu
      setxy 140 – 140
      pd
13. Challenge 4: 

The final picture should look like this:

Is there any way we could make our code simpler?  Some of the algorithms repeat instructions.

Success steps:

• Copy instructions carefully
• Press play to run program
• Make instructions to draw simple shapes including forward, left and right
• Check instructions carefully for mistakes (bugs)

If you have finished, try working through these debugging challenges!

And if you finish that…!  Start a new file and start with this code.

• reset
• setpensize 5

Can you draw a letter?  ~(Diagonal letters will need rt 45 or lt 45)