The popular South Brookline Senior Socials are back at the Putterham Branch Library starting March 9. Preceding the kosher pastries and hot coffee will be free yoga class for seniors, “Gentle Chair Yoga,” described by organizers as intended for those unfamiliar with the practice or who might have “difficulty getting on or off the floor.” The town’s Public Health Department is sponsoring the weekly classes, led by Brookline resident and yoga instructor Karen Wenc. Yoga will run 10:30-11:15 a.m. each Friday through March 30, with the social, which is cosponsored by the town’s Senior Center, following from 11:30 a.m. to 1 p.m. Reservations for Gentle Chair Yoga are strongly advised. To reserve a yoga spot, call socials coordinator Regina Millette Frawley at 617-469-0052, or assistant coordinator Paula Coelho at 617-232-3038. No reservations needed for the socials. The branch library is at 959 West Roxbury Parkway.