As a parent -- here are some questions to ask your son's teacher because as a teacher and parent her repsonses about his behavior seem very vague.
When are his most fidgity times -- morning, afternoon, during seat work, during group time on the floor, independent work time, or during something he might not want to do or understand how to do...
How does she respond to him when he isn't doing what she wants him to do? And if it is not effective (which if the behavior is continuing, it obviously is not), what else has she or can she try that you can reinforce at home...
What is think time? What is the purpose and what is he supposed to do -- is he doing it while he is in think time or is think time not a consequence that affects him
How many times does she speak to him before he goes to think time -- how many warnings and how does he know he has been warned.
THese are a few to start you....I am not a believer in the 'color dot or card' system -- it is often not enforced consistently, nor do the kids always know and understand what exactly they can get a 'red dot or card' for --
Be easy on your son (is my advice) -- reward him for the green dots -- more time with you, pick dinner, more computer time, something that is not materialistic. I would stop the punishing at home -- it doesn't seem to be helping, does it? And for a second grader the school day is in the past and he may not even be relating the two -- it is too late for such consequeces...
Every teacher hates to hear this -- but maybe he needs a little more challenging work -- if he is academically on grade level or above, he may not feel challenged (don't use the word bored -- teachers hate it!) -- OR maybe she can find some leadership roles for him to help keep him busy when he is not focussed.
Hope this helps...
T.
After reading other response to you -- I have to add -- don't jump to testing or doctor's or labels -- I am a teacher -- don't go there yet, especially if this is the first time you have heard of this behavior -- it could have to do with where his seat is in the classroom, who he sits next to, etc. etc. --investigate -- find out what all the teacher has tried and if all she has tried is the dot/card system, ask her to try other things -- not ALL kids respond to this behavior management system. Schools often have Student Support Teams or something similar that you can request your son be taken to - this is not for special education -- it is simply a team of teachers (at least where I teach) that talks to you and the teacher and offers suggestions for the teacher and you -- things that might not have been tried before, etc.
DON'T JUMP TO LABEL YOU CHILD -- PLEASE!!!!!!!!!!