I have a very strong-willed 6yo DD who is always convinced that she is right and her logic infallible (she gets it from me 
). As a result, if asked to do something that doesn't fit in with her master plan, she has an absolute melt-down. With no warning or in-between stage, just from happy to screaming in zero seconds. If you ask what's wrong she just screams louder and lashes out.
We've tried calmly pointing out that we can't fix whatever the problem is unless she uses words to communicate instead of screaming. We've pointed out that being violent is not ever going to get her anything except angry parents. We've tried to come up with coping mechanisms like writing/drawing her feelings. We've tried calm negotiations (difficult when you're already 10 mins late for school due to her refusal to get dressed and she won't say why), we've tried punishments. I just don't know what else to try.
This morning, for example, she was doing some drawing before school. She was asked to stop drawing and get her shoes on as it was time to go (and she's not supposed to do any "fun" activities until shoes are on, bag is packed and she's ready to step out of the door anyway). Cue meltdown. DH finally got her to calm down and say what the problem was - she wanted to finish her picture. I said she could finish it after school as it was time to go. She resumed the melt-down as she wanted to finish it then and there. She screamed and screamed, hit me, refused to put her shoes on and had to be dragged off to school. Later on we got a phone call that she had pinched a boy in her class really hard - probably as a result of still being wound up from the morning.
She has had similar trouble at school all year - stropping and screaming when asked by her teachers to do work instead of playing and being a huge disruption in class. She regularly refuses to get changed for PE because she "doesn't like it". (We asked why she doesn't like PE - apparently it just "isn't fun").
So, how do you cope with a 6yo who has her own definite ideas about what she should be doing at any given time and throws violent tantrums when she is told that she needs to do something that doesn't fit in with her plans?