My son is 8 years old and in second grade. as the school year progresses his attitude and behavior is declining rapidly. It started out that he was a class clown. always talking and making jokes. Then he claimed that he was being bullied. When we found out that wasnt true, that he was actually having emotional outbursts during class, like crying hysterically and yelling trying to get his point across. He is a very smart kid, but his grades are suffering,because he either rushes through his work, or flat out refuses to do it. I, as well as his teacher, are tired of having the same conversation everyday. .He has just been suspended from school, for unacceptable school behavior. He was refusing to do his work, and was shaking the table which was causing other kids to not be allowed to do their work. I am at my wits end. I have tried everything. grounding him. no tv. no video games. spanking him. He is now having wild emotional meltdowns at his classmates as well as his teacher. I dont know what to do. rarely does he have an outburst at home, so I cant figure out what is triggering his behavior.
My son was having similar issues, but in his case they were pretty much from his very first day in school. The fact that your son started after changing schools is hopeful.
The rushing through and the clowning around are often signs of boredom. Perhaps his previous school already covered certain topics. Perhaps they are moving at too slow of a pace. Perhaps the work is not tailored enough individually.
When I was a kid I nearly failed spelling class the year I won the school spelling bee, largely due to boredom. I adapted to the boredom by taking on extracurricular activities, getting placed in more advanced classes, and during the lecture of one class I would do homework from the previous class. If you can identify when your son is getting bored, the teacher might be able to help with those sorts of activities.
Refusing to do work can also be a sign that your son doesn't understand the work. That was mostly the case with my son. He wasn't paying attention to directions and therefore didn't know how to do the work. Maybe he missed some prerequisites from his other school. Maybe they are moving at too fast a pace for him. Maybe he is so bored that he isn't paying enough attention to know when something new is being taught. In this case, individual tutoring is the way to keep him from falling behind his classmates.
Note the contradiction of work perhaps being too easy and perhaps being too hard, but having the same effect. It's quite possible your son is experiencing both, maybe in different subjects. That can make it difficult for the teacher to adjust. Maybe his previous teachers were better at teaching to your son's learning style. Maybe he had friends at his previous school that helped keep him in line.
You mention your son does much better at home, does that include with homework? Our son was completing more work in an hour at home than all day at school, so we decided we may as well be homeschooling him. That has worked out pretty well for us, but I realize it's not feasible for everyone. It's something to consider, though. We can move at his individual pace, and move on before he gets bored, or spend more time if he's having trouble grasping something.
Even if you don't decide to try homeschooling, your son's going to need a lot more individual customization than he is getting now. You might look into starting a 504 plan or your jurisdiction's equivalent, perhaps getting a child psychologist involved to suggest some specific accommodations.
Karl Bielefeldt's answer is fantastic, but I would also consider the possibility that perhaps your boy is engaging in attention-getting behavior. You mentioned that he is fantastic at home with a special needs and two-year-old sibling. You also said he has previously been getting good grades and judging by your post I'm assuming he's been well behaved up until now. I can relate to your situation both as a parent and as a person who grew up with a special needs sibling. My own 9 year old boy has been having some behavioral issues lately (not as severe as you, but just as out of character.) My brother has severe ADHD and is also brilliant and was, to put it mildly, all-consuming of my parents' time, energy, and focus.
Your boy sounds so much like mine...my 9 year old is great great great with his younger brothers, he helps out around the house, is smart, funny, and generally easy going. His brothers are a handful! We were treating him like he was much older than 9, based on his responsible behavior, but he still has the emotional needs of, well, a 9 year old. An 8 (or 9) year old child values respect and acceptance by adults. So, to a certain extent, we were helping him by giving him responsibility, but were hurting him by not rewarding him for his grown up behavior. Praise is very important, so easy to do, so easy to overlook, and, it's free.
Fairness is also high on their priority list. Kids this age are almost obsessive about fairness. They count fruit snacks, turns, and keep track of how many minutes so-and-so got to play on the swings. It might not be conscious counting, but it's there in their subconscious. The lesson he needs to learn is that fair does not mean equal. He's probably smart enough to understand that from a vocabulary angle, but you may need to provide examples. My boy gets upset sometimes that my husband and I spend about an hour getting the little ones to bed, and he gets a 5 min tuck in. We had to point out that he gets a full hour of us to himself every morning before school before the kids get up. Then, it was a non-issue.
Regardless of what motivation your child has for acting out, it needs to stop. I see that you have already gone down the punishment road. Now, I would suggest you try to give your boy appropriate rewards for good behavior. This will most likely be more effective than punishment for bad behavior. Discuss the rewards (whether they are good or bad) for certain behaviors with him. It will help him feel included and respected, and will also make it "fair" since he will have had some input and can anticipate a definite consequence for an action. Let him know that you and the teacher are working together. Good behavior at school means rewards at home, just like bad behavior at school has led to punishment at home. I had to get daily reports from my son's teacher for months. It eventually became weekly reports, and then nothing at all. Each week where he earned good reports every day (good, not necessarily exceptional) he got to stay up an extra hour to watch a movie on Friday night. A single bad day was punished immediately, and, Friday night was off the table. This way, he had a much bigger incentive to behave than misbehave. This is just an example of what worked for us, your house/situation will require your own unique formula.
Finally, as Karl mentioned, it may just be a personality incompatibility between your son and the teacher. My son has had two teachers so far that he did NOT do well with. He was a "troublemaker " to both of these teachers, and went from bad to worse pretty quickly, until we all started working together. At the ripe old age of 9, he's pretty much figured out that sometimes people just don't like each other, but you have to get along anyway. If this ends up being all or part of the problem, using the rewards system will still work. Some folks disagree with the reward system, you can check it out here and admittedly, I find the arguments against it logical, but, like any tool it's all about how you wield it. In some cases, like yours, it can get you "out of the woods" and back on course. It will build confidence at best, and will be a crutch until the school year ends at worst.
I hope this helps.