My five year old can't go a day without causing harm to his teacher.
My five year old son started kindergarten three weeks ago. The first day he did great but every day there after I get multiple calls about how he isn't able to stay in class for even an hour. He has kicked punched slapped poked spat at and pushed his teacher. He also throws these ginormous fits. He does have problems with his speech where he will require speech therapy. We have tried multiple methods from talking to him to taking toys and movies away. Nothing seems to work it's getting to the point that the school does not want for him to come to school. I'm so confused as to what I should do I know this is stressful for the school my son and myself.
I would have him evaluated for sensory impairment or sensitivity, as well as ADHD/Impulse control issues, as well as possibly (but probably not) Oppositional Defiant Disorder by a Psychiatrist and an Occupational Therapist.
If he is having a difficult time communicating with his teacher, he could be getting frustrated.
Without knowing his Pre-K history, or homelife history, it's hard to say what exactly is going on. My son just started kindergarten as well, and has some sensory issues. We adopted him when he was four, and he has been in OT to help with sensory issues and impulse control since he was 3. He still struggles, but he has learned to self regulate much better, and also can tell me when he doesn't think he is going to have a good day.
Aside from evaluation, here are the things that have helped my son:
To help with regulation, my little guy takes deep breaths, which we have taught him to do by putting his hand on his tummy and filling it "like a balloon" for 5 counts, and then breathing out his nose for 5 counts. We also do "thinking chairs", which we can ask him to take, but sometimes he will take because he just needs a minute.
Also look into the "turtle tuck" which is a great book for learning to handle your emotions.
Consistency is extremely helpful for our son. Have a meeting with your sons teacher and discuss the rules/schedule at school. Keep the same rules, and even on days off keep the same schedule. Discipline and Reward should be as similar as possible. Make sure your son understands that you talk to his teacher, and that you are all working together.
When he is calm, like after dinner or before bed, while he is lying down, talk to him about how he felt and what made him act like that. This can help both of you identify triggers, and then you can clue his teacher in as well. I noticed that when my son was talking about it he would complain that his head was itchy, and that this was an anxiety response. We communicated this to his teachers, who now will let him take a thinking chair to calm himself before he gets beyond what he can handle.
5 year olds have a difficult time with a lot of new stimuli in general, but kids who are struggling need EXTRA sleep! Try an extra half an hour bedtime on school nights for starters. The first week of school my son would come home cranky, and I would let him go "read" in his room, and check on him 5 minutes later to find him fast asleep till the next morning! He was in bed at 7:30 before, but now we have him in bed at 6:30, and he seems to be doing much better.
We use positive reinforcement by celebrating when he has a good day, and surprise treats on occassion for a string of good days!
It can be difficult, but you are doing a good job by supporting your child and not excusing his behavior!