Are you trying to hint at any repercussions for your module having a high failure rate?

They can resit in October. If they do not get a massive warning shot by nulling their results, they will continue cheating. An alternative - if the office should be reluctant to punish them, and you have no discretion to null them, is to split their marks across all groups - so if 6 groups have the same submission, they each get a sixth of the mark. If they complain, you say, you say, if 6 do the job of 1, you have to split the reward, "your decision". But better to null and to mark a 1st warning; with harsher penalties applied the next time.

@AlexanderWoo high failure rates are frowned upon in our department. It's an unwritten rule that the ideal failure rate is 0% and I'm already feeling pressure from the other modules I teach where I get ~15% failures every year. This is also a new module and I don't want it to have a bad reputation.

@CaptainEmacs something like this would indeed make sense, but I'm not allowed to make any judgments on matters of academic offences, so my only two options are to either report them or do nothing. If the committee nulls them, they'll still have to score >75% in October.

I don't have a whole lot of sympathy for cheaters, even if they are international students, but it is possible that they either didn't fully understand or didn't believe the extent to which "cooperating" is often cheating. In the orientation events, was there any kind of feedback loop, such as a quiz given to the students to ensure that they understood?

@ElizabethHenning no, there wasn't a quiz, but it's a very good idea to include one in next year's induction week events!

@CaptainEmacs dividing the grade by the number of groups doesn’t make sense.

@DanRomik Apart from the fact that you do not really give a good justification why not (as with money, nobody really knows what a grade is, but a good approximation is proof-of-work; esp. if it is accumulated during an exam/assignment rather than a holistic quantity, there is no reason why it could not be treated as a currency), I personally would agree that the best course of action would be nulling the submission. Unfortunately, in view of bean counter rules increasingly contradicting academic common sense, it is appropriate to apply bean counter logic to approximate academic logic.

@DanRomik All that division of marks of course only applies between candidates that you can prove have colluded. Of course in short answers, nobody who happens to find the similar looking obvious/short solution would be punished; similarity in obvious short solution is not proving collusion. In any case, the suggestion is just to help OP counter non-academic impositions by their department in a non-ideal world.

Screw the 'cultural aspect'. You can't allow cheating for some students based solely on where they come from and disallow it to others.

@ElizabethHenning Having witnessed many of such examples, I am sorry to say that, while one might think that the students have no experience in the matter and therefore more forgiving or lenient, when it comes to investigations, one often wades through such cascades of lies before coming to the truth, that it is very clear that most know precisely that it's not permitted. It seems that they only really register that they better not try it when they see that the investigations are followed through and its outcome followed up upon by concrete and very tangible consequences.

I've worked at a university where there was a principle enshrined in the academic regulations that, if the pass rate on a module was less than 95%, the module leader was required to explain themselves at the end-of-year assessment panel meeting. However, in calculating the pass rate, any student who had been found to have committed (or was still under investigation for) academic misconduct was excluded from both the numerator and the denominator. (I'll also add that I didn't find explaining myself to the panel particularly difficult, on the many occasions when I was required to do so.)

OP, this being an Engineering programme in the UK, it's accredited by the Engineering Council, right? If the cheating is as blatant as you suggest and you don't report it, I'd say there's a strong chance that, at your next reaccreditation visit, a member of the accreditation panel will notice the cheating and be decidedly unimpressed.

both the ones who copied the answers, and the one(s) who provided them - "Aiding and abetting" is just as much a criminal offence outside Academia as "committing a crime yourself". If the students are idiotic enough to think they can get away with something as blatant as turning in exact copies of the same project, they deserve a worse punishment than just "failing the course," and if your (so-called) academic establishment permits that sort of behavior, it would be entirely reasonable to close it down completely IMO.

"this was the case last year when a similar case of collusion was taken to the academic offences committee" - did you tell your students about this recent piece of history? It sounds like a piece of information like this, delivered early on during the first session, might have made an impact. Might be something to consider going forward.

"if the pass rate on a module was less than 95%, the module leader was required to explain themselves at the end-of-year assessment panel meeting" I imagine that those panel meetings would have been pretty busy last year...

So the single thing you do is refer them to the committee? You can't even change the grades? For example, you aren't allowed to find out who wrote it and whether they purposely shared it, or not? I wonder if the committee wants to do all the work, or if they simply expect they'll have to take over from overwhelmed instructors.

Engineering is supposed to have a code of ethics. As a member of the public, I would feel deeply uncomfortable knowing that there are engineers working out there who are willing to take the "easy way out" of doing hard work.

@JohnMcSimon Well, then you are in bad luck. However, you can still null them and give them a good preparation for the retake. You still can report the marks and the suspected offenses with your recommendations and it's the duty of the department to decide whether it wants to uphold pass rates or academic integrity.

@OwenReynolds My only option is to report this to the AO committee. Lecturers are not allowed to make any judgement regarding collusion or plagiarism because the students can then appeal to the school. Although in my case there is no doubt the students have copied each other's solutions, word for word, in general two or more students may arrive at the same solution and/or do the exact same mistakes without collusion. This is why this is handled by an independent committee.

@StephanKolassa yes, this was mentioned by a colleague at the beginning of the academic year during the induction week. I believe we communicated very clearly to the students that the school has a strict policy against academic offences.

@CaptainEmacs I'm not advocating leniency, I'm advocating prevention. The ultimate point here is to discourage students from cheating in the first place.

Lots of gleefully vindictive comments here with nobody applying common sense. If people submitted the exact same project without even trying to make it look different, the obvious explanation is that they misunderstood "group assignment" as meaning any amount of collaboration is allowed. You should still penalize them for it (e.g. make them all turn in a new one) but the amount of moral grandstanding here is excessive in my opinion.

@knzhou Please. Give them a little credit about this. It's more likely they did "know" they were supposed to do their own work, but it didn't sink in that they would actually be punished for all submitting the same assignment.