The term Computer Assisted Learning (CAL) covers the area of using the computer to assist in the learning situation. CAL is known as CAI (Computer Assisted or Aided Instruction) in the United States. There is a variety of methods by which a teacher can use to produce computer assisted learning programs. The Science Teachers' Authoring Facility (STAF) is available at the University of Canterbury for the authoring, or writing, of CAL programs. It has a specialised high level authoring language, the STAF language.