Basics of play: Roller derby is a contact sport played by two teams of five members simultaneously skating counterclockwise on a circuit track. Each team designates a scoring player (the “jammer”); the other four members are “blockers.” One blocker can be designated as a “pivot”—a blocker allowed to become a jammer in the course of play. The jammer wears a helmet cover bearing two stars; the pivot wears a striped cover; the remaining members’ helmets are uncovered.
The bout is played in two periods of 30 minutes. Point scoring occurs during “jams”: plays that last up to two minutes. During a jam, points are scored when a jammer on a scoring pass (every pass a jammer makes through the pack after the initial pass) laps members of the opposing team. Each team’s blockers use body contact, changing positions, and other tactics to assist its jammer to score while hindering the opposing team’s jammer. Certain types of blocks and other play are violations; referees call penalties and require violators to serve time in a penalty box.
Jams: Play begins by blockers lining up on the track’s starting line (the “pivot line”). The jammers start from the “jammer line,” a second starting line 30 feet behind the pivot line. With a starting whistle, the blockers may begin to skate; when either the last blocker in the pack crosses the pivot line or the blockers’ actions result in there not being a pack, a set of two short whistles signals the jammers to start.
The pack is the largest single group of blockers containing members of both teams skating in proximity, arranged such that each are within 10 feet of the next. While blockers are required to maintain the pack, they are permitted to skate freely within the area of the track beginning 20 feet behind the pack and ending 20 feet ahead of it, an area known as the “engagement zone”. The first jammer to exit the front of the pack, having legally passed all blockers at least once, earns the status of “lead jammer. Once earned, lead jammer status cannot be transferred to other skaters, but certain actions (notably, being sent to the penalty box) can cause it to be lost. After the initial pass through the pack, each jammer scores a point every time he or she laps a member of the opposing team (including the jammer who is not lead).
The lead jammer can stop the jam at any time by signaling to the referees. This is done by repeatedly placing both hands on their hips. If the jam is not stopped early, it ends after 2 minutes. If time remains in the period, teams then have 30 seconds to form up for the next jam. Team members typically rotate between jams from the 14 players on the team’s roster. Designations may change between jams: a pivot in one jam might be the jammer in a later jam.
Jammer wears a helmet cover with two starts on each side. Jammer scores points by lapping opposing team
Blockers do not wear a helmet over. Blockers assist the team’s jammer to progress through the pack while hindering the opposing jammer by preventing her from passing.
Pivot wears a striped helmet over. A pivot is a blocker who may be designated as a jammer during the course of a jam. Also, establishes team strategy during play.
(Images and content courtesy of http://www.fracturemag.com/, http://en.wikipedia.org/wiki/Roller_derby, http://aucklandrollerderby.com/about-roller-derby/ and http://ilovememphisblog.com/2012/06/365-things-to-do-in-memphis-180-go-to-the-roller-derby/)