Reception 5 YO behaviour issues - school may be escalating it

[doublemuvver]

my DS is just 5 and has been having issues in school since starting in Sept. His twin sister is in same class.
DS is not listening and has started to answer back and lashes out when told to do something he doesn't want to do. Teacher has said he is very bright and does well with his school work but he should have settled by now and they are going to "flag" his behavior and the HT will get involved.
We have talked to him and he says it's because no-one plays with him (this is not true, he does have several friends though there is a distinct lack of boy friends outside school as my friends all have girls). DD doing v well and settled in much better, perhaps he feels he is in her shadow?
I'm going to arrange a meeting with school instead of snatched chats at hometime.
At home he is whingy but generally a good boy. Often moans he has "nothing to do" whilst DD happily plays with whatever is there. TV use limited. Has great relationship with his twin on the whole. He sleeps 7-7 and eats well.
Bit bewildered and obviously concerned. Any advice??

Has his teacher identified his "flash points"? The times when he is most likely to lash out or answer back?

Or is it random?

You could ask her if there is any pattern....ie, at playtime, or lunchtime...or carpet time.

That will give you a starting point towards working out what the trouble is. If as you say he is academically capable, he could be not getting challenged enough...or he could simply be hot headed and still young.

Have they suggested anything such as a school based sticker chart to help encourage his good behaviour? It's all very well them telling you they are "flagging" his behaviour but they need to put something in place to help him combat this.

Does he listen or lash out in other environments without you present, like when visiting a friend without you, parties, clubs?

He is really behaved when we're out in fact they are both a pleasure to take out. He only has away time from us when he's with my folks and they say that he is fine too. They were both in nursery before school and there were no issues raised there, just some general boisterous boy behaviour.
I agree to find out whether there are any triggers for his "flash points". There is a parents evening in about 3 weeks time but I think I'd like a one-to-one with teacher before that.