Two programming environments (microworlds) were developed in the context of the PhD by Stelios Xinogalos (2002) and the Operational Programme "Pythagoras II" (2006) respectively:
objectKarel for an introduction to Object-Oriented Programming
Karel for an introduction to Procedural-Imperative Programming
The two environments share the same features and differ in the educational material (theory, activities) incorporated in their learning module.
The two environments are freely downloadable and relevant research carried out with them can be found in the relevant subpages.