An introduction to object-oriented programming with a didactic microworld: objectKarel

The objects-first strategy to teaching programming has prevailed over the imperative-first and functional-first strategies during the last decade. However, the objects-first strategy has created added difficulties to both the teaching and learning of programming. In an attempt to confront these difficulties and support the objects-first strategy we developed a novel programming environment, objectKarel, which uses the language Karel++. The design of objectKarel was based on the results of the extended research that has been carried out about novice programmers. What differentiates it from analogous environments is the fact that it combines features that have been used solely in them: incorporated e-lessons and hands-on activities; an easy to use structure editor for developing/editing programs; program animation; explanatory visualization; highly informative and friendly error messages; recordability. In this paper, we present the didactic rationale that dictated the design of objectKarel and the features of the environment, including the e-lessons. In addition, we present the results from the use of objectKarel in the classroom and the results of the students' assessment of the environment.