Team: A maximum of 5 girls per team on the track at a time: 1 pivot, 1 jammer and 3 blockers.
Game: Two* or 3 periods played between 2 teams
Period: 14* or 20 minutes
Formation: Players line up in 3 rows, in a 2-4-2 formation. Pivots up front, and blockers behind. The jammers start 20 feet behind the pack. Skating no more than arms length apart is the ideal pack formation.
Jam: 2 minute phase during which Jammers try to score points by passing opposing team members. A jam may be called off by a referee, the lead jammer or the clock.
* Most leagues have 3 twenty minute periods per game, but since my league, the Dallas Derby Devils is so big - we have 4 teams and 2 games per bout so we have 2 fourteen minute periods.
Jammer: The primary point-scorer, the jammer must pass the pack once, then each opposing team member she laps is a point scored for her team. The first jammer through the pack while staying in bounds is designated the lead jammer, and can call off the jam by placing her hands on her hips. The jammer is identified by the star on her helmet.
Pivot: The pivot sets the pace for the pack and is the last line of defense. She is also responsible for calling out plays on a moments notice; all skaters look to this position for guidance. The pivot is identified by the stripe on her helmet.
Blocker: Blockers try to stop the opposing teams jammer. Blockers also knock around the opposing teams blockers to assist their own jammer through the pack.
Once the pack has lines up, the referee blows the first whistle; the pack takes off. At the double whistle the jammers sprint to get to the front of the pack. The jam will last 2 minutes unless it is called off by the lead jammer, a referee or the clock runs out. The end of a jam is indicated by a quad-whistle blow by a referee.
*Illegal use of the hands and feet (grabbing, holding, pulling or tripping) *Blocking from the rear *Elbow blocks above the shoulders or in an upward, downward or jabbing motion. *Clothes-lining an opponent *Blocking from out of bounds *A blocker or pivot engaging the jammer while more than 20 feet forward of or behind the pack.