Roller Derby in a Nutshell...
Two teams compete with a maximum of 5 total players from each team on the track at any time, 4 of these skaters are blockers and they form what is called "the pack" and 1 is a jammer, they score the points.
The pack is made up of 4 blockers from each team, for a total of 8 skaters.
Pivot Blockers wear a striped helmet cover.
Blockers usually position themselves close together in a wall formation to form a a tight pack.
All blockers start between the Pivot Line and the Jammer Line.
Jammers wear a star helmet cover (a.k.a "panty"), and is the scoring skater.
Jammers start on the Jam line, which is 30 feet behind the Pivot Line.
Penalties are awarded for ANY action that affects the safety of the game in a negative way.
One long whistle will blow when a penalty is dished out, and penalised skaters get to visit the "sin bin" for 30 seconds where they can reflect on their bad behaviour before returning to the track.
The Game Run Down
The Jam: maximum 2 minutes long
The Bout: as many jams as it takes to get through 2×30 minute halves
The Pack lines up between the Pivot Line and the Jammer Line, Pivots in front to set the pace.
The Jammers line up at the Jam Line.
1 whistle starts the jam and Jammers are released.
The jammers must work their way through the pack, passing all blockers.
The first jammer through the pack legally (without penalties) is declared "lead jammer" by the refs. Advantage: the lead jammer can call off the jam any time they want, by placing their hands on their hips repeatedly.
After the first pass, the jammers score points by lapping opposing team members. For each opposing team member they pass, they score 1 point.
The goal of the rest of the team (blockers) is to stop the opposing jammer from passing them and scoring. At the same time, they knock around the opposing team's blockers to help their jammer score.
4 whistles means the Jam has been called off. The players have about 30 seconds to line up for the next jam.
The team with the highest points at the end of the bout wins.
See more details of WFTDA official rules.