My mother-in-law told me this great story of her friend's preschool granddaughter. Apparently, she was in a lot of trouble at school this week for dragging another little boy by the arm in anger. She left quite a scratch on him, and her teachers let her parents know about the incident. Her mom talked with her at home and the conversation went like this:
"Okay honey, so what should you do the next time a kid is upsetting you INSTEAD of scratching his arm?"
"Next time I'll make sure he's wearing long sleeves!"