For a child, no matter what the situation is when he complains that "it's not fair", his young mind is being tortured by unequal treatment. At this time, the emotional understanding and support of parents are the best placebo for the child. First, appease the child's unequal emotions, and then persuade the child, so as to prevent the child from being hurt by the bad emotions, and let the child understand what true fairness is.

2. Stand firm, there is no room for negotiation.
Emotional understanding does not mean that there is no principled stand. Parents must stand firm when reasoning with their children, and let their children understand that there is no room for negotiation on principles. If he thinks his sister's cake is big and his cake is small, you can tell him it's because his sister is older and needs to eat more to get full. If the child has difficulty accepting it for a while, you can promise him, and if he is not full after eating this piece, you can allow him to add a small piece. If he refuses to clean up his messed-up toys, you have to patiently tell him that it is fairest to do his own thing or offer to help him clean up together, and then slowly let him develop the habit of cleaning up his toys. Remember not to give him a cake the same size as his sister because he is crying unfairly, or let him pick up his toys, so that the child will get used to this way to achieve his goals.
3. Parents should set a good example for their children in their daily life.
Parents are the initial imitation objects of children, so parents' words and deeds are very important. Parents should lead by example in the things they ask their children to do in their daily life, such as not crossing the road at red lights, not making loud noises and fighting in public places, not being jealous when others get what they like, and so on. In this way, when the child asks questions, the parent's explanation will be more convincing: "Only when the green light goes and the red light stops, there will be no traffic chaos." "If you don't make noise in public places, people will not influence each other." "Other people get what they like because of their hard work."
In addition, if parents are indeed unfair, for example, they usually ask their children to go to bed at 9 o'clock, but one day they want their children to go to bed earlier because of their parents' reasons, it is recommended that parents respect their children's opinions and abide by their own rules.