Finding the rhythm: Sadie Overstreet, 9, counts off the beat with drumsticks while rehearsing with her band, a group gathered during Girls Rock Lab – a program of Spark Central – on Thursday, Aug. 10, 2017, at in a Spokane Public Library meeting room. The girls have spent the weeklong camp writing and rehearsing an original song, which will be performed at 7 p.m. Friday at the Bartlett.