Sometimes if you can't snap them out of blame with "this isn't about blame" you can let them have their say, but follow it through with calm logic.
"Explain to me - how is this the teacher's fault?"
The answer is something like, "If she hadn't nagged me I wouldn't have got angry."
"So you got angry - why? Was it useful to get angry? Were you hoping that getting angry would make her listen to you? Did it work?"
Work through the encounter. If it can be shown that the teacher contributed you may need to acknowledge this, but make sure you can point out that getting angry was not a useful thing to happen. Walk through it again - what else could he have done? Even if the teacher was wrong to nag, how else could he have responded, to defuse the situation? It takes two.
Often, working on WHY they got angry can help with, "What did getting angry achieve? What would you have liked to achieve? If you could go back and re-live it, how do you think you could have improved on the situation?"
Here you have carefully steered it away from guilt/innocence; blame/not blame, and back to cause and effect; action and consequence. By rehearsing and role-playing you can freely admit that it's not fair for a difficult child to have to be extra careful to not lose temper, but it's still a desirable goal. "Other kids hit back; why can't I?" was a common question in our house.
Our answer was, "Because you're the weird kid, that's why. An average kid can hit back and people will accept that he was provoked. You hit back and people will say it's because you're disturbed and dangerous. We know that's not true, but they don't. So don't do it - life's not fair, people believe the wrong thing, but trying to act like you're no different in this will not help you one little bit. And the important thing here - for YOU to win, in the long term. Not hitting back will achieve that."
The best thing is to always focus away from blame, don't buy into it, but shift the concept always, back towards consequences and alternative paths.
And recognise our difficult children will take longer to learn this, as well.
Marg