This spring, school gates around the world slammed shut. By early April, 1.5 billion students were staying home as part of broader shutdowns to protect people from the novel coronavirus. The drastic measures slowed the spread of SARS-CoV-2, the virus that causes COVID-19. However, as weeks turned into months, pediatricians and educators began to voice concern that school closures were doing more harm than good, especially as evidence mounted that children rarely develop severe symptoms from COVID-19. By early June, more than 20 countries had started to reopen schools. When Science looked at strategies from South Africa to Finland to Israel, some encouraging patterns emerged. Together, they suggest a combination of keeping student groups small and requiring masks and some physical distancing helps keep schools and communities safe, and that younger children rarely spread the virus to one another or bring it home. But opening safely, experts agree, isn’t just about the adjustments a school makes. It’s also about how much virus is circulating in the community, which affects the likelihood that students and staff will bring COVID-19 into their classrooms.