To teach the triangular Logo turtle a new commandin effect, to write a computer programthe child simply types the word TO followed by some step-by-step instructions. For example, here is a program that tells the computer to draw a circle on the screen:
REPEAT 360 [RIGHT 1 FORWARD 1]
The word END tells Logo that the definition is complete. Logo responds by typing CIRCLE DEFINED. The next time the computer sees the command CIRCLE, it will locate a copy of the definition and start executing the instructions it contains. Repeating the commands within the brackets, it makes one tiny right turn and...