Commands
When you are programming with Logo you are pretty much talking to a turtle :). You give it commands and it will respond to them by drawing what you tell it to draw. Below is a list of what commands the turtle recognizes.
forward x
This will tell the turtle to move forward x pixels
backward x
This will tell the turtle to move backward x pixels
right x
This will tell the turtle to rotate to the right x degrees
left x
This will tell the turtle to rotate to the left x degrees
pen-up
This will tell the turtle to lift its pen up and stop drawing
pen-down
This will tell the turtle to put its pen on the canvas and start drawing
color x
This tell the turtle to switch to a different colored pen. For example, to make the turtle draw red lines, just write the line “color red“! The available colors for you to choose from are:
red, orange, yellow, cyan, blue, green, purple, brown, pink, black, white, and magenta
thickness x
This command tells the turtle to use a pen that is x pixels wide
cursor x
This command changes the cursor to a different images. Possible values for x are:
0 - No cursor
1 - Arrow
2 - Turtle
3 - Airplane
example: To change the cursor to a turtle write the line “cursor 2“
background x
This command changes the background of the canvas to a different image.
0 - blue sky
1 - brown
example: To change the background to brown, write “background 1“
speed x
This command will tell the turtle to speed up or slow down. Setting x to 0 will stop the turtle, and setting it to 100 will tell it to go as fast as it can. Any value from 0 to 100 is valid.
Loops
One very useful feature of most programming languages is the concept of loops. Loops will tell the computer to repeat certain commands as many times as you want. For example. Say you want to draw 10,000 squares on top of each other, you could manually write out over 80,000 lines of code, but my guess is that that would get boring after a while. Instead, you can use a loop to draw a side and rotate the turtle 80,000 times with only writing 4 lines!
repeat 80000[
forward 20
right 90
]
To use a loop you need to use the repeat command. This is how it is structured:
repeat x[
//everything inside these brackets is repeated x times
]
Comments
If you ever want to make notes to yourself or others in code, you can simply add two slashes and then write whatever text you want. For example if you wanted to tell someone where you were drawing a square you could simply write:
//this is where I am drawing the square