Many schools are having stay in cohorts or pods in order to limit the spread of germs. The CDC published the following:
Cohorting forms groups of students, and sometimes teachers or staff, that stay together throughout the school day to minimize exposure for students, teachers, and staff across the school environment. Ideally, students and staff within a cohort would only have physical proximity with others in the same cohort.
This simple story give children information about cohorts, in an easy to understand way.