Teaching Loop Testing to Young Learners with the Code Critters Mutation Testing Game
Philipp Straubinger, Lena Bloch, Gordon Fraser
TL;DR
The paper addresses the challenge of teaching loop constructs and testing concepts to younger learners. It extends the Code Critters framework with loop-based recipes and loop-testing tasks framed by mutation testing, implemented as second-stage levels unlocked by base-level performance. The study with 29 secondary-school students shows that loop-based levels promote engagement but reveal substantial learning barriers around loops and conditionals, suggesting gradual introduction, hints, and adjustable difficulty as design priorities. Overall, the work demonstrates a viable path for integrating core programming concepts with game-based learning to support early CS education and informs future refinements for broader adoption.
Abstract
Serious games can teach essential coding and testing concepts even to younger audiences. In the Code Critter game critters execute short snippets of block-based code while traversing the game map, and players position magical portals (akin to test oracles) at locations (akin to test inputs) to distinguish between critters executing correct code from those who execute faulty code. However, this adaptation of the tower defense genre limits code under test to basic sequences and branches, and excludes the fundamental programming concept of loops. To address this limitation, in this paper we introduce an entirely new game concept integrated into the Code Critters storyline, tasking players to test the behavior of critters collecting ingredients for a healing potion using loop-based recipes at a second-stage level. In a study involving 29 secondary school students, we observed active engagement with these new loop-integrated levels. The results highlight challenges the students face, which can inform future strategies for improving coding and testing education.