Bouncing Bulldogs, from left, Haley Malek, 13, Perry Ramsey, 11, Bri Merrigan, 12, and Emily Williams, 12, practice a dance routine that combines acrobatics, dance and jump-roping. The Bulldogs, who have won three straight national jump-roping championships, are the subject of a new film called 'Doubletime,' which will be shown Feb. 1 at Durham's Carolina Theatre.