New Trier Extension 7 Happ Rd, Northfield, IL60093 With more than 600 classes offered each year, New Trier Extension is the community education branch of the local high…More school district. Classes are available on campus and online, daytime and evening. Highlights include computer skills, aerobics, yoga, crafts and ballroom dancing. Day trips are also available. For a catalog of classes, visit the New Trier Extension web site.