So, I think a few things you can consider: it is a great lesson to him to learn to read directions. If he wants to go ahead, I think you should appreciate the opportunity to teach him to focus on reading instructions. Assuming he truly "gets it" and is just mis-reading the directions, that is something BEYOND important for him to learn to do. As gifted parents, we are always seeking stretch goals, and opportunities for our kids to work hard at something. So this is a great chance to teach him the importance of following instructions. Of course, I think there is a chance that he's just stretching to do exercises that he's not ready for (as opposed to just mis-reading directions). That's not bad, just a different issue.
He is definitely misreading the directions at least in the occassions/examples I have seen sent home and the incidents he recounts for me (this is not to say there isn't another side to the story that has validity also). And yes I did tell him that he needs to focus on reading instructions and that is something BEYOND important for him to learn to do. I myself am also impatient with instructions (once (as an adult no less!) in law school I did an entire exam "wrong" because I didn't bother to really read the directions and that cost me a bit grade-wise). I can relate and have burned myself with same problem so I talked to him about as a person who has struggled and been burned by the same thing. So, totally agree with you and teacher there. Also, although he reads on grade level, reading is not something he likes or even does all that well, in my opinion (he has a vision disorder but I have always suspected some sort of dyslexia; regardless, 'reading' is quite taxing for him and he routinely mistakes words particularly small words). So, it is totally fitting and within his personality to just want to jump right into doing calculations rather dealing with reading words and/or he very likely is also misreading words and has no idea. And, yes, I did take the opportunity to tell him he needs to take the time to get the reading right so that if he works ahead he can do so properly following the instructions, etc. Having said all of that, I am sure he needs instruction at least in some situations (he is not EG) - but he seems to need a faster pace. He says he sits for "a half an hour waiting for the others" so that they as a class can move on, which I am pretty sure is an exaggeration so I am thinking he is more likely waiting around for 10 maybe 15 minutes. But that is still a long time - at least he is working and not 'carrying on' or distupting others! At least he is trying to do math at math time! However, sometimes I am not so sure the time is a total exaggeration becasue yesterday after he "worked ahead" he also apparently had time to write (which takes him forever, btw) out times tables and the teacher also gave him addition/subtraction drills (which he also worte) ... So at least yesterday it sounded like he was ahead and "waiting" for quite awhile.