What are good manners in school?

Treat everybody you meet with respect and sensitivity; consider how they are feeling, and think about how you'd like to be treated under similar circumstances. If you yourself are treated in a disrespectful manner don't take it personally; there could be many reasons for the person's behaviour which very likely have nothing to do with you. Simply behave towards them in the way you'd like them to treat you, and keep a pleasant expression, Not too much smiling, they could think you're mocking them. People who behave discourteously are frequently upset or insecure, worried or angry. You can't really define a list of rules because every person and situation are different. Learn to really listen, don't assume you know what they're going to say, and don't interrupt. Learn to notice what's going on around you; if someone is struggling with a pile of books or groceries, open a door for them or offer to carry some. If a family member is clearly tired or unwell, suggest they sit and relax while you make coffee or a snack for them, or offer to do some shopping or cleaning or whatever you think they might need at the time. Don't just think about what you'd like in their place; think about what they might really need.