From the booklet:
The child is requested to think of an object that is either animal, vegetable or mineral. The program will now try to guess what the child has thought of. It asks questions about the object and then guesses what the object is.
If the program does not know the object then the child can 'teach the computer' about the object. The child also needs to give the program information to tell the object apart from the other things it knows.
At the start the program knows only a little, so it is easy to teach the computer things. The more it knows the more the need to look things up! The information stored can be saved and reloaded at any point in order to continue to build up what the computer knows at a later date.