A Chicago-area hockey instructor has some explaining to do after video showed him teaching youth hockey players how to fight. The video shows ex-hockey pro Libor Ustrnul instructing kids - ranging from ages 11 to 13 - to take turns punching each other on the ice. Ustrnul defended the drill, saying the boys are wearing gloves and helmets and that "most of the time, they're laughing". If things get too physical, he blows the whistle. Ustrnul says he's teaching the kids "to stand up for themselves and respond." How would you react if your child took part in one of these drills? Should you just know this is what your kids sign up for? Yes, fighting is known to happen in hockey, but why? Should it be banned?