Whole-class, high-quality peer tutoring is achievable with minimal effort or expense for teachers

One-on-one tutoring by adults is among the most effective educational interventions, yet it remains prohibitively costly to scale. Peer tutoring offers a promising alternative, with substantial evidence supporting its efficacy for both tutors and tutees, but implementing it often requires additional time, planning, and teacher training—barriers that limit adoption. This paper presents Slonig (https://slonig.org), a lightweight, open-source peer tutoring app designed to overcome these challenges by ensuring proper student matching, guiding tutor behavior with a built-in algorithm, and controlling quality through structured feedback and game theory mechanisms. Slonig enables scalable, same-age peer tutoring with minimal teacher oversight, no lesson preparation, and integrated training for student tutors. Pilot classroom implementations with peer-led onboarding demonstrated rapid adoption and usability across age groups. While further research is needed to quantify learning gains, these early results suggest that peer tutoring, when supported by well-designed software, can serve as an effective and scalable instructional method even in resource-constrained settings.