The worst of the COVID-19 outbreak is likely yet to come. But it’s worth taking a moment to think about why it took so long to close the nation’s public schools.

School districts nationwide finally began to close brick and mortar schools at the end of the second week of March, a full week after many college and universities sent students home.

Students, teachers, and parents are now embarking on the largest experiment in online instruction this country has ever seen—and many important questions remain. Will there still be standardized testing? What about kids who don’t have reliable internet access? How will districts ensure data privacy for students and families?

Another question: why’d it take so long to begin the experiment?

It’s simple. Public schools are public goods. They provide basic educational, social, emotional, and even physical needs to not only students and families but also entire communities. Closing them has effects that ripple out beyond school doors. As Erica Green wrote in the New York Times, mass school closings could “upend entire cities.”

Just look at the numbers:

The nation’s public school system serves more than 50 million students, many of whom have parents who work and need childcare during the day.

The federal National School Lunch Program serves food to over 30 million kids annually. Many families rely on school to feed their children meals throughout the school year.

There are more than 3.1 million public school teachers, many of whom are already struggling to get by. Teachers, paraprofessionals, front office workers, bus drivers, janitors, and other school staff rely on public school jobs to make ends meet.

But perhaps most importantly, public schools provide kids with the opportunity to learn alongside their peers. Schools are where the community comes together to learn and grow regardless of skin color, income level, sexual orientation, or any other difference.

Only public institutions—not private markets—can make sure that these basic needs are available to everyone.

The next few days, weeks, and months are uncertain, but one thing’s for sure: we’ll be learning how much public schools really matter to all of us. Some—teachers, administrators, and school staff—already know how important they are.

Chicago Public Schools has already handed out more than 90,000 meal packages including three days’ worth of breakfast and lunch.

Teachers in Noblesville, Indiana, decorated their cars and drove through students’ neighborhoods to honk and wave.

Bus drivers in Washington State’s North Mason School District are delivering bagged breakfasts and lunches to bus stops throughout the rural district.

(The Network for Public Education is compiling stories of how the public school community is serving the nation during the outbreak.)

Public schools matter because we all benefit from them regardless of whether we have a kid in school. Public schools matter because they’re public goods.