Blinded by their Plight: Tracing and the Preoperational Programmer

In this paper, we present evidence that some novice programmers have the ability to hand execute (“trace”) small pieces of code and yet are not able to explain what that code does. That evidence is consistent with neo-Piagetian stage theory of programming. Novices who cannot trace code are working at the first stage, the sensorimotor stage. Novices who are working at the preoperational stage, the second stage, can trace code but do not yet have a well-developed ability to reason about the code’s purpose, other than by induction from input/output pairs. The third stage, the concrete operational stage, is the first stage where novices can reliably reason about code. We present data from think aloud sessions that contrast the behaviour of preoperational and concrete students while they attempt to reason about code