We demonstrate that heat inhibits learning and that school air-conditioning mitigates this effect. Student fixed effects models using 10 million PSAT-retakers show hotter school days in years before the test reduce scores, with extreme heat being particularly damaging. Weekend and summer heat...

Only half of SAT-takers retake the exam, with even lower retake rates among low income and underrepresented minority (URM) students. We exploit discontinuous jumps in retake probabilities at multiples of 100, driven by left-digit bias, to estimate retaking's causal effects. Retaking...