Syntes: Lichand et al. (2026) — Rio de Janeiro school phone ban raised test scores (working paper)

Källa: Lichand, G., Moreno-Louzada, L., da Costa, T., & Gentzkow, M. (2026). The Educational Impacts of School Phone Bans: Evidence from Brazil. NBER Working Paper 35233. https://doi.org/10.3386/w35233 — working paper, not peer reviewed when used (2026-10-11).

Verified numbers (full author PDF, 27 April 2026 version, read 2026-10-11)

• Setting: Rio de Janeiro municipal school system (more than 650,000 pupils, 1,557 schools in 2025). A municipal decree banned non-pedagogical phone use in classrooms from August 2023 and school-wide from February 2024; phones may still be brought to school and kept stored.
• Design: difference-in-differences comparing middle schools (grades 6–9) that had partial or no phone rules before the ban (treatment) with schools that were already strict (control). Full sample 196,757 pupils in 325 schools; matched sample 97,380 pupils in 154 schools (549,969 pupil-quarter observations). Two years of quarterly test scores before the ban; event-study pre-trends flat.
• Phone use (principal survey): share of schools where most or all pupils used phones in class: treatment 52 % before → 19 % after; control 40 % → 15 %. Many pupils still bring phones (72 % of treatment schools report pupils bringing them most days).
• Test scores (Table D2, matched sample): school-wide ban × treated, maths+Portuguese index +0.061 SD (SE 0.028, p < .05); with student fixed effects 0.073; with CRE × post 0.084 (p < .01); maths +0.077 (SE 0.037, p < .05); Portuguese +0.045 (SE 0.024, p < .10). Classroom-only phase: +0.010 (SE 0.021), not significant. Authors: about one fifth of a typical year's progress.
• Who gained: concentrated among low prior achievers; larger in grades 7 and 8; concentrated in schools whose principals reported that phone use fell.
• Authors' caveats: the design compares schools with different exposure to one ban, not a ban with no ban; treatment schools were poorer and scored about 0.1 SD lower at baseline; a harder test from 2024 applied to all schools; phone-use data are coarse retrospective principal reports. Their extrapolation to about 0.2 SD against no ban is a calibration, not a causal estimate.

Role for C6

Supports / survive-and-log (2026-10-11): genuine kill-condition test (field DiD of freer prior access vs a stricter restriction, on learning outcomes). Kill fails because scores rose after the school-wide ban. Adds a middle-income, city-wide setting to the claim's "gains in some settings" clause, with gains mainly among low achievers (as in England). Note that the classroom-only phase showed no significant gain, in line with the Chilean classroom-level null (Shi & Villarroel 2026). Working paper: recheck when published.