Dear Jeni,
You certainly have a difficult situation in your household. Children can be very stubborn at times; but they can also have problems that, as a parent, we know nothing about. You would think raising our own species would be easier than it is!
Well, here are my thoughts that may be of some help to you, and I hope they give you some confidence as a parent. Many things our children do or don't do are not our fault! We are not "bad" parents. But, in truth, our kids can be downright naughty at times!
Remind your son that doing homework at this age is his responsibility. If he doesn't do it, it's on him. Explain to him (as you might have done already) that going to school and following instructions is his JOB. That is the main job he has right now. His wages are his grades. If he learns to do his job well, he will be able to handle other jobs as he grows older.
If he absolutely refuses to go to school, take the responsibility to call the school and tell them what is going on. They will send a "truant officer" to pick him up and bodily (if necessary) take him to school. That in itself might solve your problem. (I had similar trouble with my second oldest about the same age. It may be a case of "school-aphobia" or something similar. It is not to be taken lightly because that is a serious disorder in some children.)
Make sure your son's pediatrician and any specialists you might have for him, as well as his school counselor and principal know the situation. They will work with you. Furthermore, the whole family has to support whatever decision you (and the advisors) make for dealing with your son's behavior.
Perhaps some private, away-from-the-home, heart-to-heart talks with him might eventually reveal why he is being so stubborn about this. Maybe something happened in first grade that he never talked about that discouraged him from doing homework. He may just be lazy; or he may be tring to control his own world; or he may find it difficult to concentrat at home. To him, "home" is not "school" and vice versa. Also, if he truly thinks he is so smart and doesn't need to do the work, let him find out by watching his grades more carefully. If they go down, he will know he must do the homework.
I know one tactic recommended over and over again is to be sure your child does his homework at the same time every day. When he comes home from school, he may be hungry and tired. If you give him 30 min. to an hour to eat a healthful snack or meal and play outside for a while (no computer until evening after homework is finished) before he starts his homework (it may take a while to establish this pattern), you might eventually get some results.
Patterning gives children security, and security helps them learn better. Of course, something like that will take your undivided attention; so plan on being CONSISTANT and don't give up or give in! Remember, you are the parent. You are the leader.
Do not overlook or dismiss the possibility of a mental or emotional disorder at this age. Psychological disturbances are as problematic as a broken leg to a marathon runner, or a broken arm to a professional tennis player. They should be diagnosed or ruled out in order to help your son become the best person he can be.
Finally, if your family attends a place of worship, you might ask your pastor or priest or deacon if he will come to the home and you, your husband, and son pray together about the homework situation. This will impress upon your son the vital importance of "doing the paperwork for his job" and perhaps change his outlook on the issue.
Also remember, whatever happens, make sure you, your religious leader, the school, and your medical personnel are all working together to resolve this issue.
Discipline is "doing the same thing the same way the same time the same day until it sticks!"
Punishment is "repremand for deliberate disobedience and must be appropriate for the crime."
Use them both wisely.