One of the major difficulties with teaching the first programming course is input/output. It is desirable to show students how to input data and output results early in the course in order to motivate the students and so that they can see the results of their programs. Output is also a useful tool for testing programs. However, in most programming languages input and output are esoteric and the techniques for performing input and output must be learnt by the students at an early stage,

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... when they are trying to understand the basics of programming. We argue that input/output operations need not be taught in the early stages of a course if the language environment provides appropriate tools for testing programs. This assertion is demonstrated by reference to the Blue objectoriented language and environment.