I don't think anyone suggested the instructor had any excuse. He was, it seems, guilty of an absolutely heinous crime - trusting his student to do something simple and get it right. Most instructors do that all the time. After all, we have to let Bloggs out of the nursery at some point. So, for example, most of us let our experienced students do the 'A' check at the start of the day. But if they miss something, it's the instructor's 'fault'.
Moral of the story...don't ever become a flying instructor; it's too risky.
Sorry Whirly I disagree. It is the Instructors responsibility as PILOT IN COMMAND to check NOTAM. It is disgraceful that he did not. Not only does it set a bad example to the student but it could have endangered life.
As an Instructor I check the NOTAM every day before teaching and then quiz the student to make sure they have done so as well. If they have not then it is a teaching opportunity to improve things.
Moral of the story is the flying Instructor has the opportunity to ensure that the student becomes a competent and safe aviator, this includes proper pre flight planning, inspection etc and not doing so is just lazy teaching.