Saying "well done" may be the best way of getting children to behave at school, according to a new study.
In fact, telling off a pupil in front of all their mates may be the worst thing a teacher could do.
Instead, teachers involved in the study praised the kids that were doing well in lessons and saw the others around them improve their behaviour as well.
But the teachers were also warned not to be too nice to the kids, and only to praise them when they deserved it.
Experts from Liverpool John Moores University worked with six primary and secondary schools in the north west of England to test their ideas.
They found that before their training ideas were used around 78% of the pupils were behaving and concentrating. After the new ideas were used that jumped to 94%.
One of the heads of the research, Dr Jeremy Swinson, said: "What every teacher wants is for children to do as they have been told, in other words, to behave.
"The most effective strategy of getting anybody to do as they are told is to be positive."