percentile when you compare the 2021 to 2019. obviously 2019 was before covid, and here's the reason why it's down so much in lower income areas or at least one of the reasons why. if you ask basically the parents of those students who had to stay home because the schools were closed, did your children have trouble completing your school work because of tech problems, in the lower income areas, look at that, income adults said that their children had problems, tech problems versus in the upper income areas, it was just 18%. lower income and minority groups were hit the hardest, at least when it comes to children learning. >> harry enten, i appreciate it. fascinating to look at the numbers. perspective from dr. danny benjamin, distinguished chair of the abc science collaborative. appreciate you joining us. some schools in multiple states around the country are shifting to online learning or pausing the return to in-person learning to a few days to a few weeks. do you think that will protect students from becoming infected with covid or is keeping the schools open better? >> keeping schools open is