Even before classes began for Northwestern University freshmen, about 550 had their first course in local volunteering on Sept. 23. Deployed to various District 65 schools, the students spruced up gardens and playgrounds. At Lincolnwood School, they raked the yard and added fresh compost to the plantings around the school sign. Haven Middle School’s small garden along Green Bay Road received a facelift as well. Across the lawn, at Kingsley School, students raked cartfuls of wood chips onto the playground and spread compost in the garden areas.