Northwood Elementary School students arrive for their first day of classes on Sept. 1. All Mercer Island School District schools with students in grades 1-12 began in-person, full-time classes on that day. Kindergartners were set to start in-person, full-time classes on Sept. 3. All students and employees will be required to wear masks in their buildings and on school buses. Andy Nystrom/ staff photo

Northwood Elementary School students descend the stairs en route to their classes. Andy Nystrom/ staff photos

A Northwood student skips with joy on the first day of classes. Andy Nystrom/ staff photo

A mother hugs her children before they head toward the Northwood school building. Andy Nystrom/ staff photo

A Northwood school administrator helps a student map out her schedule. Andy Nystrom/ staff photo