Many times, it is difficult for children to have personal experience only by oral preaching, but we can't really put children at uncontrollable risks. What shall we do? Try this and see how it works.
Tell the children that if they don't listen to the command, they must accept the corresponding punishment as the price they must pay.
Once the school rules and regulations are violated, those who are light will be punished for standing for a class, and those who are heavy will be disqualified from various honors, or accept the task of cleaning stairs and handrails.
Then clean up all the rubbish in the classroom. If not, clean the teacher's office.
In short, tell children that if they don't correct this habit, they will have a lot of tasks to complete.
Tell them what the stakes are. Although the children are young, it does not prevent them from understanding the teacher's good intentions, and they can also compare the differences.
After weighing the pros and cons, the child's behavior can be corrected slowly.