In the USA, a technique called the Parent-Child Game has been developed that has proved successful in giving many parents a means of establishing discipline without tears. The game depends on doing the opposite of what harried parents and teachers usually do. This means giving positive attention to the child when it is well behaved and ignoring behaviour that is disruptive but not harmful to others.
What children want most in the world is attention. Truculent children get all the attention when they are naughty and are ignored when they calm down. Without realizing it, the parents are training them to behave badly.