Wow you cannot let this continue, I have to agree with Deborah's advice. I also have a six year old son that is wonderful in school, an angel right BUT recently he has tried to get the best of me by being smart and rude when talking to me. Funny thing he does not do this with his father. At first I too began to scream and get frustrated but I told myself whom am I arguing with? A 6-year-old child? This should not be happening, we are the parents and we need to respect and expect the same back even if they are 6 years old. I baby my son a lot and I have found that the moment I change my tone, not scream just change my tone and facial expression when talking to him, I notice a difference in him. I have noticed that talking to him and explaining to him in a serious way what he is doing is wrong really works! I have to make sure to keep the seriousness for a bit until I noticed his behavior has changed for a period of time, so he understands that its not an acceptable behavior.