You are the first and most important teacher of your child. Disciplining a child means teaching a child an self-discipline is developed from positive experiences, hour by hour, day by day. When there is conflict, the first step is to take time out. Show ways to review solutions, options, and consequences of choices. Demonstrate that patience and fairness will work for everyone in the family.
Appropriate anger is sometimes acceptable.
Violence is not an alternative. Personal safety rules should include how to get help. Parenting is probably the most difficult job in the world but many people find it to be the most rewarding. Schools should be organized on the principles of non-violence with rewards for appropriate behavior at every level. Students should be expected to treat all others as they want to be treated themselves.