Unfortunately, this quick example is something that teachers and school administration often don't get. If you make a threat for misbehavior, you must follow through, otherwise you have seriously undermined your and every other teacher's credibility, and then you will predictably get misbehavior on almost every lesson since now.

Unfortunately, the reality is often that teachers make empty threats, hoping that using big words will scare students, and when this does not work, they rationalize not following through by "they are just children" and "they need to get a second chance", although some students already had literally hundreds of "second" chances. And the worst thing is when teacher insists on the punishment, but after a phone call from parent, the school administration overrides their decision. Of course students share their "success stories", so the next day the whole school know about the winning strategy.