General Good Looking = Effective It's hard to learn from poorly drawn figures and cumbersome user interfaces. Well chosen colors and layout go a long way to making things effective. Maybe it's just that my concept of beauty includes this kind of elegance. Don't keep People Guessing I hate when a lecture or book is set up as a long series of steps with some surprise at the end. Tell people up front where the discussion is going and why it's worth being motivated to read.

Pictures & Animations Every Concept has a Picture Associated with it this is for easy visual recall when referring to different topics. Pictures make things easier to digest. Nobody wants to read a huge block of text and equations. Every Animation has Key Frames saved as Pictures People shouldn't have to download and watch the animation for the discussion to make sense.

Java Applets Easy Startup When applets load, they should already be set to a state that does something interesting, not ask the user for a thousand parameters before it starts. Interesting Presets If there's an option to type in a function, provide several as interesting examples accessable by buttons. Sliders, not Text Boxes The Java applets are trying to give an intuitive sense of how different variables affect things, not a pure calculational tool. Nobody wants to type in numbers, but they should always have the ability of using an exact value if they want.