Blockers form a(n open) tripod at the jammer line. The jammer tries to get past the tripod, and the blockers try to block the jammer.

• If the blockers can keep the jammer until the pivot line, that is where the exercise round ends (position of first set of refs in the picture)
• If the jammer gets past the blockers at any point, the blockers will start a chase, that can last untuil the first corner (position of second set of refs in the picture).
• During this chase, they will assume that the last opposing blockers is at the pivot line; the blockers therefore have to bridge accordingly!

Tip: this is also an excellent exercise for refs to train their "no pack" and "out of play" definitions at the front of the "pack"!

For blockers: being able to keep the jammer behind the tripod, using an open tripod. Being able to communicate well who will chase and who will bridge. Providing a good bridge for your chasing teammate. Chasing a jammer effectively and stopping them/hitting them out and recycling back.

For jammers: being able to break through or move around the tripod. Being able to "win" a chase every time and escape from the pack.