D.C.
I work at a daycare as an assistant...with 2 year olds in the morning and 1 year olds in the afternoon, so I work with children just your son's age. Don't worry...they do transition, although some take a little longer than others. I have a set of brothers (one in each of my classes) who both had a tough time transitioning just within the past couple weeks as a matter of fact. Since I'm in hte 2 yo room when they come it the older one is the one I work with during the transition time. What I found worked for me was I would take him outside to help me "look for fire ant nests". He loves being outside and just a few minutes of being away from the others would help him calm down. Or if we were already outside I would think of something to help me with inside, such as make copies of the daily sheets we take home, get something from our resource room, etc. If your son's teacher doesn't have an assistant maybe the director or assistant director could try this for him. Now I get a big smile from this little guy as he walks in the room (most days, lol), andhe just started 4 weeks ago. I also reassured Mom daily with his progress, which I'm sure your son's teacher is doing.