19 April 2021, Baden-Wuerttemberg, Heitersheim: Corona self-tests from students lie on a table at St. John's Secondary School, along with labeled clothespins. After more than four months of lockdown, schools were supposed to reopen to all children and young people. But Corona infection numbers are above the threshold of 200 infections per 100,000 residents in seven days in a number of counties, forcing schools there to remain closed. Other counties are approaching the threshold. Photo: Philipp von Ditfurth/dpa