An open program, i.e. a program where there is a part or a separate program where you can make your own exercises, might often increase the accessi-bility. One is then able to influence a lot of the above mentioned when creating the exercises. Symbols can be hard to understand, but with a completing text or an aloud reading of it, it becomes considerably simplified for most pupils. If you know where to look, you will find things easier. It is also easier to understand the function of a symbol if you primarily use the same functions as in other computer-programs, and that they return to the screen in the same position in all other parts of the program.
Quick response Avoid all possibilities to misunderstandings at runtime.
When clicking, it should either have an immediate response or none at all. There can not be any kind of waiting time, not even a second. This is one example among many, of something that creates confusion.