Derbypedia...
Team: There are
14 players on a team with 5 players on the track during a jam, 1 Pivot, 3
Blockers, and 1 Jammer
Periods: A game
consists of two 30 minute periods.
Jam: Two
minutes of play. The periods are divided up into jams. There is no limit to
the number of jams you can have in a period. The clock does not stop between
jams.
Pack: Two teams
of 3 Blockers, and 1 Pivot - 4 players from each team for a total of 8 players
makes up the pack.
Formation:
Pivots in the front, blockers in the center of the pack, jammers line up 33 feet
from the pack.
Jammers: Wears
the star on her helmet. These girls are speed freaks. They make their way
through the pack and score points by passing their opponents in-bounds, while
trying to obtain lead jammer position.
Lead Jammer:
The first jammer to break through the pack legally (without penalties and
without going out of bounds) has the advantage of being able to call of the jam
at any time. They do this by putting their hands on their hips.
Pivots: Wears
the stripe on her helmet. They set the pace of the pack and are responsible for
calling out plays. They are also the last line of defense for the opposing
teams jammers. Pivots can take over as a jammer. This sneak attack maneuver is
called “Passing the Star”.
Blockers: They
are the brains and brawn of the pack. The must play offensively by working
together to block the opposing teams jammer and defensively by assisting their
own jammer.