Starting next season, a system of cameras will determine whether to award a first down rather than trot out a 10-yard chain. But humans will still decide where to spot the ball to begin with.

Youth soccer games seem to unleash the worst in adult behavior. Parents and coaches yell at refs, the players and each other. Adults' sideline behavior has resulted in a national referee shortage.

For the first time, a woman will be among the referees working during a Super Bowl. Sarah Thomas is part of a growing number of women officiating at the highest level of men's sports leagues.