Abstraction is one of the most fundamental ideas in computer science (CS), and as such, according to Bruner, it should be taught spirally, starting as early as possible and revisited at every level of education. However, teaching CS abstraction to novices is a very challenging task, and CS educational research has often demonstrated students'…

The TeachScheme! Project aims to reform three aspects of introductory programming courses in secondary schools. First, we use a design method that asks students to develop programs in a stepwise fashion such that each step produces a well-specified intermediate product. Second, we use an entire series of sublanguages, not just one. Each element of…