I know at Barrett Elementary School, where my son goes, the walk-to-school day is a rather festive and honored event, with the number of walkers increasing for the day. Parents bring cameras and shoot photos of huge groups of children.
Please watch for kids on the streets.
As well, Arlington Public Schools says that all middle school buses will practice emergency evacuations as the buses arrive at the schools. Potential delays may slow drop-off. Please take that into your morning commute calculations.