Roller derby is played in increments called jams. Each jam last up to two minutes. Both teams field up to five skaters at the start of the jam. Four of these skaters are called blockers and one is called the jammer. The jammer wears a helmet cover with a star on it and scores points for the team. The blockers are playing both offense and defense at the same time and together they make up what is called the pack. The two jammers start each jam behind the pack and must get through all of these skaters for an initial pass before they can begin to score points. When the initial pass is complete a jammer can score one point for every opponent they pass with their hips. The first jammer out of the pack legally is declared lead jammer which means they can end the jam anytime they want before the two minutes are up. Sounds easy right?