There are Java applets sprinkled throughout these web pages.  Some of them are useful to get to regardless of which lesson you are on.  Some are just fun to play with.  So, I'm including a list here for easier access...

• Calculator Applet
• Color Numbers Applet
• HowTo DrawBoard Applet
• HowTo DrawO Applet
• The Game of Life Applet
• Mastermind Applet
• Racquetball Applet
• SpaceWar Applet
• TicTacToe Applet
• BIG TurtleGraphics Applet
• tiny TurtleGraphics Applet