the c.d.c. says wearing a double mask adds significantk ge protection. the new research tonight.s back to school. teachers in the third largest district agree to go back to the classroom for the first time in nearly a year. plus, is president biden backing away from his promise to get kids back to school in his first 100 days? president biden visits the pentagon. his new task force to deal with china; and grappling with racism and extremism in the military. preparing for record cold. ice in the south, snow in the northeast and midwest. what you need to know. rescued. how three people survived on a deserted island for 33 days. and, the covid quilt. an inspirational little girl who wanted to honor the americans lost to coronavirus. this is the cbs evening news with norah o donnell, reporting from the nation s capital. o donnell: good evening to our viewers in the west and thank you for joining us. we are going to begin tonight with that breaking news, chilling new video of