The workdescribed here was undertaken at the University ofBrighton between 1986 and 2006 in order to assist Computer Science students to acquire practical software development skills, primarily in the areas of real-time systems and object-oriented programming. The contribution to knowledge represented by this work is the development of a set of design principles for educational software, and a variety of software artefacts which demonstrate the applicability ofthese principles. The publications span two decades and describe artefacts covering a number of areas in the curriculum related to software development. They address a range of topics within Computer Science due to the rapidly-evolving nature of the discipline, but they have led to the development of a common philosophy towards the development of educational software, and they each provide an original approach to the topics they address. The success of this philosophy and the originality of the work is evidenced by the fact that they have each been adopted by other educationaf institutions, have been widely praised by students and educators, and have in many cases led to related work by others. This critical appraisal concentrates on describing the evolution of a coherent educational rationale which underpins the various artefacts described here, and on placing this more firmly within the context ofestablished educational theory.