To which almost every parent that ever had a child in daycare says: “Duh!”
Seriously though, several child studies came out in the last week. They imply viral transmission will likely happen in schools both ways (child-to-teacher and teacher-to-child), viral load in children is at least as high as in adults, and early closure of schools probably was a key differentiator in determining severity across different states.
DOI:10.3201/eid2610.201315
DOI:10.1001/jamapediatrics.2020.3651
DOI:10.1001/jama.2020.14348