MicroWorlds Lessons

MicroWorlds EX™ Lessons

Lesson Two: Intro to Procedures - Create and Test Your Own Commands

The LOGO computer language comes with a few built-in commands already in the brain of the turtle and the software. These are called PRIMITIVES. The include fd, bk, rt, lt, cg and others. (Click here for more info on those basic terms).

When you create NEW commands for the turtle to learn and carry out, these are called PROCEDURES.

Step 2: Procedures

A) WHERE to Start?

You need to type in your commands in the proper Procedures area:

To type PUBLIC commands that are available for ALL turtles in a given project to follow, just click near the bottom on the right side of the screen on the "Procedures" tab so you can type in new commands for all of the turtles to follow.
To type PRIVATE commands for just that turtle (or any clones or copies of that turtle you might later make), right click on the turtle and choose "Open Backpack", then click on the "Procedures" tab on the bottom of the dialog box so you can type in these private commands.

B) How to Start and End a Procedure?

All procedures should start with TO and a name, followed by line-by-line instructions, followed by a final line that ONLY says: END (& Enter)

For example:

to star
repeat 5 [fd 100 rt 144]
end

C) How Do I Build a Procedure?

If you repeat the basic elements of a square: fd 47 rt 90 four times in a row, you will get a square.
You can do that by:

to square
fd 47 rt 90
fd 47 rt 90
fd 47 rt 90
fd 47 rt 90
end

or use the repeat command, like this:

to square
repeat 4 [ fd 47 rt 90 ]
end

D) How to SLOW DOWN a Running Procedure?

Sometimes you might like to slow down a running procedure so you can see each step in the process. To do this, click on the Processes tab on the right side of the screen near the bottom. Then choose from the three colors at the top of that same tall white box:

Green for Full Speed Ahead
Yellow for Slow Down, Please
Orange for S-L-O-W To A C-r-a-w-l!!!

You can switch these back and forth during a running process.

E) How to STOP a Running Procedure?

Stopall Stops all turtles and procedures. You can activate this in 3 ways:

Type this command "stopall" in the command center on the grey bottom left portion of your screen and hitting Enter.
Use the mouse and pull down Edit and click on Stop All, or
Click on the red "Stop" sign near the right end of the top toolbar.

Lesson Three: Graphics in MicroWorlds EX - Using Color and Shapes

Main MicroWorlds EX Tips Page