Parental involvement in children’s education is often constrained by limited information, low agency, and weak incentives. This study examines whether a government-led education system can address these barriers through a low-cost, low-touch intervention implemented by public schools and teachers in Kebumen, Indonesia, where teacher capacity is moderate but learning outcomes have stagnated. The intervention comprised three components: teachers provided regular updates on students’ learning progress; parents could write responses directly to teachers through a feedback section; and monthly leaflets offered simple, practical ways to support learning at home. The intervention was implemented entirely through existing school structures at a cost less than USD 1 per student over 14 months. Our randomised results show greater parental engagement and communication with teachers, and higher teacher motivation and support for students. Ten months later, mathematics scores improved among lower-grade students, while reading motivation declined among higher-grade students. A follow-up qualitative study indicates that parents’ limited ability to assist with learning and insufficient teacher support during pandemic-induced school closures constrained progress, particularly for older students.