Play some ultimate frisbee to get them bounding. Try some indian runs (jog in a line, runner in back sprints to front, repeat).
Track Game: Divide the group into two teams that are roughly equal in ability and tell the kids to start running laps until you say stop (set a time limit that you'll keep to yourself). At the end of each lap, the person who is last is captured and does drills by the start line until someone on his or her team finishes a lap first. The person who is first either counts as having run two laps or frees a teammate (the default if a teammate is captive). If the person who is first and the person who is last are on the same team, the last place finisher continues. Whichever team totals the most laps in the time allowed is the winner. The point of keeping the time limit to yourself is to deter the better kids from time-trialing the run in a bid to be first every lap. The unknown time keeps the kids bunched. Keep track of laps on your clipboard.