I think he is just trying to say he spoke to 'a' year group. If he said he spoke to a class, would that help? You are right that it is not that specific, a yea

I think he is just trying to say he spoke to 'a' year group. If he said he spoke to a class, would that help? You are right that it is not that specific, a year group maybe one class, multiple classes or part of a class.