This paper discusses the problems of making algorithms 'transparent'. The approach taken has been to define a Formal Language for the problem domain which describes the main steps in the algorithm under discussion. This Formal Language has been used in a system which allows the student to enquire about selected parts of the algorithm and in a facility which comments on the student's explanations of certain parts of the algorithm. Some indication is given as to how the system's facilities can be

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... extended to answer a further range of questions, but it is concluded that in order to make substantial progress in this pursuit a single representation for algorithms is required which can be both executed and used as a basis for explanations. 1.