20-Years Later: A Replication Study on Teaching CS1 Concepts

Introduction: Computer Science Education does not have a universally defined set of concepts consistently covered in all introductory courses (CS1). One approach to understanding the concepts covered in CS1 is to ask educators. In 2004, Nell Dale did just this. She also collected their perceptions on challenging topics to teach. Dale mused how the findings of a similar survey conducted in later years would compare with her results. Objectives: We answered Dale’s call to consider changes in teaching CS1 concepts by performing a replication study 20 years later. Our goals were to determine how the teaching of CS1 concepts has changed and to identify concepts educators perceive as challenging to teach. Methods: We created a survey based on Dale’s original study and added concepts from the CS2023 recommended curricula to include CS1 concepts for today’s teaching practice. We used a mixed-methods approach to analyse the 178 responses from CS1 educators. Results: Our survey results show Python is predominately used to teach today’s CS1 courses, with educators continuing to teach basic programming concepts similar to 20 years ago. However, our survey shows recursion continues to be challenging to teach, with most secondary school educators perceiving it does not belong in CS1. Today’s educators also teach less of the CS1 concepts from 20 years ago, such as inheritance and polymorphism, and have a limited focus on ethics and professionalism in their courses. Participants also found good learning behaviours like thinking and planning strategies challenging to teach. Conclusion: We conclude our paper by discussing the challenges of conducting a replication study, which includes reproducing studies with limited or no access to the original instruments. We present future research opportunities raised by the study’s findings, including how to support educators in teaching the challenging concept of good learning behaviours and further refine curricular guidelines to remove ambiguity on concepts covered in CS1 and CS2 courses.