Zach Larkin had just finished teaching a history class when he challenged Austin Lazarus to the match.
With students urging him on, Lazarus accepted and the contest began.
Witnesses say Larkin had to use both hands and all his body weight to beat Lazarus. The force and torque broke the boys arm.
“He was screaming all the way to the specialist,” she claims in the suit.
The Orange County Register reports Austin's mother, Kim Zippwald, called it "poor judgment" in the civil suit filed this week against Larkin.
“If he hadn’t escalated it and his arm had just broken in a normal arm wrestling competition, there’d be no lawsuit,” Lazarus’ attorney, Doug Vanderpool said.
The school won’t comment on the case, but Zippwald said her son still suffers from the injury.
“The arm has healed but is slightly crooked, she noted. “It’s still not perfect.”