Simplify the following text for a Grade 5 native English-speaking person.
Original: If the lead jammer does not call off the jam ( or if there is no lead jammer ) , the jam runs for two minutes .
Simplified: The first jammer to get through the pack without leaving the track gets to be the `` lead jammer '' . The lead jammer can put her hands on her hips when she wants to stop the jam early .