To teach kids how to make the right decisions, the most direct approach is telling them the real consequences. Besides, another important thing to emphasize is independent thinking. Kids often follow other kids to do something, but this is not always right. A right decision is not always a decision made by most people.
Here is one example.
A= Adult, K=Kid
(During COVID-19 pandemic time, we went to a park and see several children were playing in the closed playground)
K: Hey, I want to play in that playground, too.
A: Let's read the sign in the playground first. Could you read it?
K (reading): Playground closed due to COVID-19.
A: Do you think you can play in the playground since it is closed?
K: No. But why are other kids playing?
A: Maybe they did not see the sign, maybe they do not know the virus is very easy to catch, or maybe they are too eager to play. However, do you think they are doing the right thing?
K: No. But I still want to play in the playground. I haven't played for a long time.
A: I am glad you know this is not the right thing to do. Have you thought about the consequences?
K: Well, catch the virus.
A: Do you know what will happen after you catch the virus?
K: Get sick.
A: Oh, it is not regular sickness. You have a good chance to have a fever, cough all the time, and may go to hospital for injections or die.
K: That is very bad virus.
A: Yes, it is very bad. Do you still think going to play there?
K: No. Shall we tell those kids not to do that, neither?
A: I do not think so. Their parents are around, so their parents will take the responsibility. One more thing, do you need to do whatever others do even though you know what they do is wrong?
K: I am not sure.
A: OK, let's do an example. If you see two kids throwing pens to each other in the classroom, do you think they are doing the right thing?
K: No. Bad thing.
A: Will you go telling them it is not right?
K: Yes, I will.
A: Will you also join them to throw pens?
K: No, because it is wrong.
A: Great. What if half of your class throw pens to other kids? Do you think they are doing the right thing?
K: No, they are doing the wrong thing.
A: Will you join them?
K: No, because it is wrong.
A: What if the whole class except you throw pens? Is it a right thing to do?
K: I do not think so.
A: Will you also join them?
K: I do not know. Maybe is it fun because a lot of kids do that.
A: It is not necessary for you to do a wrong thing even though many others are doing it. Things done by a lot of people do not mean those things are right. You need to learn what is right and what is right, and keep yourself from doing wrong things. By the way, since you know throwing pens are wrong, will you try to stop them?
K: Yes, I will.
A: No, you should not. You do not have enough power to stop the whole class, so what are you going to do?
K: Tell the teacher?
A: Yes, you need to find someone who has enough power to stop them, like the teacher.
K: I know that.
A: Two things. First, will you do wrong things even though lots of other people do those things?
K: No.
A: Great. Second, will you try to stop lots of other kids from doing wrong things?
K: No.
A: Great. Remember, when you do not have enough power, keep what is right to yourself, and try best to find someone who has power to stop those kids, like parents or teachers.
K: Ok, I know. Let's keep on biking~~