In this research full paper, we present a study of a cohort of non-traditional students learning to program as part of an intercalated computer science year named Year in Computing at University of Kent, Canterbury in the UK. The study uses focus group interviews with students to explore their articulations and perceptions of learning to program. During the interviews, we used Bebras puzzles as a tool for students to reflect on their own experiences in learning to program. By observing the students working with the puzzle, some of the tacit information of problem-solving strategies became apparent. We see Bebras puzzles as a way to gain valuable insights that are not as easily available when relying on conventional self-reflection in a qualitative study. Another contribution grounded in this study is the proposal of a framework describing the students' developing mental models in the beginning of their studies. The results presented here are a first iteration in an ongoing endeavour of exploring students' development of mental models. We hope that these contributions will provide teachers and researchers with a new perspective for developing introductory programming curricula and to engage in further development of our framework.
