Ask your kid about his school and how his day was. Listen calmly and offer comfort and support. Kids often wouldn’t tell adults about bullying because they feel embarrassed and ashamed that it's happening, or worry that their parents will be disappointed, upset, angry, or reactive.
There is no age to teach your children about this (bullying) when you feel they understand some one is hurting them might not be physical (verbal) they need not keep facing it.
You need to make them understand what would ‘bullying’ be like and if they are being bullied they need to inform the teachers and parents. Also, you need to teach them not to bully other kids.
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