The protests over police killings of Black people have broadened into calls to dismantle systemic racism — including in schools. In Tacoma, a Black Youth Matters march on Saturday drew hundreds of people of all ages and races. One woman held a sign that said “No Cops in Schools.” Some children wore t-shirts that said “I can’t breathe” in honor of George Floyd, who was killed by a Minneapolis police officer who kneeled on his neck for almost nine minutes.