Hi S.-
The other responders have given you good suggestions- make sure everyone is telling him the same thing. That said, if he is in a special needs preschool, he should be very happy and getting along with others. I don't know what your son's disability is, or if he has a disability, but here is my recommendation. Find out what the program is doing. Take a day off from work if you need to. This experience is important, and will set his attitude towward learning for some time to come. If your son has special needs, he should have an IEP, OK'd by you. Find out what level the 'work'is- it may be too hard. I usually recommend Montessori environments, since the public schools have recently become so accademically oriented that many children are miserable. There is a public Montessori school here in Tucson, but I don't know about the program. I also recommend that you and your son (and his teacher/s)use some sign language to help him with his daily needs when he cannot find his words.
It sounds like there is a fair amount of pressure for compliance. Make up a little check-off chart for the behaviors which are concerning the teacher. There should be about 5. There should be check-off boxes for excellent, good, fair, poor. Duplicate the form; give teacher a pile, ask for one per day, completed with date, to be given to you when you pick up your son, or? At his age, I would use stars or his favorite stickers when his score comes up. Show the scores coming up on a chart posted at home where he can see it; on the refrigerator or something like that. When the same thing happened to my son, I attached TV time as his daily reward- the levels checked corresponded to points, which corresponded to minutes of TV time. Remember that TV needs to be Sesame Street, Blue, etc., and no more than two hours daily. For TV, substitute your son's favorite activity. Try not to use food as a reward, although it is usually most rewarding. My son's chart was set up so that, even if he got all excellent scores, he couldn't get more than two hours of the activity.
Finally, the teacher should not be making all negative generalizations about your son; report her/him to his/her supervisor, and ask for what is working correctly. The teacher should also be completing charting on your son's IEP goals and objectives, if he is a special needs child. The teacher should be reporting to you on a regular basis. Most special needs children at your son's age will have a spiral-bound notebook which goes back and forth between teaching staff and child daily. Any illness, emotionally upsetting episodes, etc. should be noted, as well as med administration, dietary restrictions, items eaten, and so forth.
I should add that my son's episode (which happened in 1st grade) ended when the school demanded that I put him in the behavior disordered room, or he couldn't come to school. I am a special ed. teacher, and I knew my rights (and his). I threatened a lawsuit because they had not completed the process properly before telling me, had refused to do my chart, and in general, had been uncooperative. I told them that I was taking him out of school, found a good sitter, and let him sit it out the rest of the school year. The next year, I sent him to a private school where the teacher thought my chart was wonderful, and cooperated with me. The behaviors were history within three months.
I might also add that, if you are hoping to be a public school teacher, be very careful not to burn all your bridges behind you. There are some organizations which can help, and will send a representative in to meetings with you. Bone up on special ed. law and process, if your son is already identified.
Hope it helps - S.