Most of the races are 1000 meters (1 km) for the mosquito age group. Just reset your odometer and drive 0.5 km. Run with your little runner to that point and back, starting easy at first. Better yet, go to a running track and try 2.5 laps.
The PeeWees and Bantam distance is 1500 meters. (3.75 laps at the track)