9.1 With drawing area.

9.1.1 First example:

to ex1  
rt 1  

This procedure is recursive because the procedure ex1 is called on the last line. While executing, we can see that the turtle turns on itself forever. To break the program, we must click on the STOP button.

9.1.2 Second example:

Here are three new primitives:

to ex2  
fd 200 penerase wait 60  
bk 200 penpaint rt 6  

Now, we can execute the program. On each second, the same procedure is repeated. We obtain the seconds of a clock!