Let's start with something new. The small red triangle you see is a pen. This will draw lines and move under the direction of the buttons on the pad on the left. Try using the buttons to get the pen to draw various shapes; 'clear' will clear off the lines you've drawn.
This is an introduction to a tool we'll be using extensively in this course: a "drawing turtle", first introduced in Logo. It's a handy, visual way to introduce core programming constructs -- control structures, variables, expressions, and arithmetic. We'll progress from hand manipulation, to doing simple programs using constants and very little control, to complex programs.
Each button sends a separate message to the pen. We've configured this one so it will show you its progress as it goes....