Foo Fighters frontman Dave Grohl performed on Saturday night (May 12th) at Notes & Words, a small benefit festival for UCSF Benioff Children’s Hospital in Oakland. During the largely acoustic set, Grohl was joined on stage by his daughter, 12-year-old Violet, for a cover of Adele’s “When We Were Young,” with Violet singing and her father on acoustic guitar. They were later joined by Grohl’s nine-year-old daughter Harper on drums for “The Sky Is A Neighborhood.” Foo Fighters just wrapped up the first leg of a North American tour that will resume on July 6th in Columbia, Maryland.