Abstract

Leogo is a novel programming environment supporting an "equal opportunity" user interface which allows users to express their programming tasks through any mixture of three concurrently active programming paradigms: by direct-manipulation using `programming by demonstration'; by clicking buttons and dragging sliders in an iconic language; and by typing commands in a normal text-based language. Equal opportunity ensures that the e#ects of any interface action are simultaneously displayed across each of the three paradigms---input expressions in one paradigm cause output of equivalent expressions in the other two paradigms. Leogo is designed to promote programming skills in primary and junior schools, but the interface properties it demonstrates are applicable to a wide range of novel programming environments. Leogo's motivation, design, development, and preliminary usability study are described. 2 1 Introduction Programming skills are becoming increasingly important at work...

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