To be brutally honest, if an "open book" exam is made substantively easier by having reference to all the course/lecture material simply presented verbatim, then it's not a very good open book exam. The point of allowing references into an open book exam is to de-emphasise the role of rote memorisation. But the counter-balance should be to emphasise the role of deep analysis. If the exam is made too easy because the students have access to the full set of lecture slides, you probably haven't set an exam that's analytical enough.

On the other hand, if the challenge posed by your exam wasn't really affected just because students brought in all the lecture materials, then what's the issue?

So does your semester go 20 days? :) If the exam was in the middle of the semester, why didn't you bring up the change earlier? You said you knew that they were abusing the cheat sheet when you have seen some during the exam, right?

@Mayou36 I edited my question to respond to your comment

The first thing to grok is that you will always have one or two students unreasonably outraged about something. I had a student write a 5-page complaint letter to the department head over a 1-point deduction on the first assignment. That's just the example from this semester.

@Deepak I edited my question to respond to your comment.

Thanks. "..our quizzes do test understanding and analysis... lazy, ..they would just copy the lecture slides wholesale..." - Yes, but if your exam is really testing "understanding and analysis" then your marking scheme will be penalising these regurgitators. In fact, they'll be doubly penalised because if they've just copy-pasted the lecture materials without adequately digesting them, they'll be wasting time reading them all over again during the exam instead of thinking up a good answer. So, if your exam is robust, you shouldn't have concerns about these chaps getting away with anything.

To the best of my recollection, I've only sat through 2 open book exams in my life. Neither of them had restrictions on quantity or form of printed/written references one could bring in. One was a biochemistry practical, and the references were almost essential for supplying certain constants for a spectrophotometric assay. The other was a Human Resources exam. Bringing in the entire textbook and lecture series was permitted - however, those who didn't bother to digest the material before the exam did very badly because all the questions were about application of the points in the material.

Did you consider that you are penalizing everyone who has started preparing (using the sheet and having it ready to study in exam conditions) while the lazy ppl aren't affected? Yes, imho you're being unfair.

@Deepak Could you put your comments together as an answer? You have raised good points, and I’m afraid the comments may be moved to chat and become much less visible in the near future

@DanielR.Collins It seems you've misunderstood me. I wasn't arguing that references in an open book exam shouldn't be helpful (what would be their point then?). I was making the argument that an open book exam should be set robustly enough that bringing the entire coursework (within the bounds of feasibility) into the exam hall shouldn't give an undue advantage. This is a nuanced point about the sort of thing that an open book exam should be assessing to make the format meaningful.

If OP is in a U.S. institution, you may also want to wait until next week before parsing the answers, as many American academics will be offline for the Thanksgiving holiday through the weekend.

@ILiketocode I'll consider doing so a little later as it's late here and I have a long drive ahead of me in the morning. :)

"I don't think that bringing in all the lecture materials would help a student significantly" and "they would just copy the lecture slides wholesale and hope for the best": I'd say that there is a conflict between the two parties's expectations: either you are overestimating the exam difficulty or the students are underestimating it.

@Deepak Sure sleep and safety while driving is more important. However you may miss the chance to get some extra rep if you delay too long. :-P

@MassimoOrtolano I think the students are a little too worried about the quizzes and exams. Of course it is easy for me to say that, since I am at a stage where I no longer need to take exams...

@ILiketoCode comeon, maybe you are a little to worried about them not learning something with a printed cheat sheet then.

I tell my students they have to prepare their cheat sheets themselves, and that magnifying glasses are not permitted. I also tell them it’s good preparation for the quizzes and final.

What exactly is in the syllabus regarding the cheat sheet (i.e. what's the actual wording)? If nothing, what was announced verbally? Where, generally, are you located (country minimum; if USA, the state would be helpful)? Does the syllabus have anything in it saying that it's terms are subject to change, and a process for doing so? Does your institution have any explicit, written (available to students) policies regarding a syllabus? Do any of those syllabus policies cover making changes?

I am troubled by " I only work on what I need to do for the course in the next 1-2 weeks" and "teaching is not my highest priority". That certainly explains feeling that 10 days is enough notice, but you need to understand that your 800 students probably includes some for whom getting a good grade on your course is a high priority, and who have been working towards that weeks, not days, in advance. Is it really appropriate to be telling them that they are doing it wrong, and forcing your own short-term thinking on them?

And what did the department general office say?

The answers cover your question about the short notice, but I want to question whether having this rule at all is good. Yes, digital notes mean people can copy your slides, but they also mean you can use a font that's perfectly legible, easily rearrange and edit notes, directly copy and paste from other notes to reduce transcription errors of formulas, easily save the note sheet for use with homework or future classes, etc. Printing out all the slides as a note sheet is something you should discourage, but don't penalize people with excellently crafted digital notes because others are lazy.

What kind of material are you teaching that 10 days isn't enough to rewrite a "cheat" sheet? You're giving them a "cheat," which is like a gift, so they are indebted to you in a way. But, now that you've changed, you're back to equal in my opinion. The student is overreacting. Copy and paste in a digital format is not the same as handwritten, I agree. Stand your ground.

One other thing: Please don't call these "cheat sheets" because it will confuse many students (esp., foreign-language speakers). Recommend calling them "reference sheets" or "formula cards".

@DanielR.Collins That is a good point. It is too late to change the terminology for the current course, but I will change the name to "reference sheet" the next time that I teach the course.

I find problematic the idea that you should be in the business of forcing particular study habits. While encouraging good habits makes sense in moderation, college students are adults and probably have study habits developed over years that work for them personally. Some students might just want a quick reference sheet that doesn't take too much time to put together and review the material in another way.

@Karl The department general office hasn't responded yet. This is because I made the announcement on Saturday, and the department general office is closed on Saturday and Sunday and will reopen on Monday.

@uwnojpjm Sorry I tagged the wrong person for that comment.

@k_g US college students are not generally treated as adults, are they? Living in shared-room dorms, no alcohol, lessons in english, history, sports etc. like at school?

how do you make sure all 600 students get informed? Hoe many class room sessions are left? Are you planning to let a student fail who didnt get your last memo and is bringing an outdated cheat sheet?

@lalala We will make the announcement in the last lecture (this week), and we will also make an announcement in the learning management system

So the chance that every student gets informed is almost zero? The real mess will be the student who missed that announcement and fails the exam (by either you taking away his wrong cheat, or failing him because of fraud (using non aporoved material)). Better take names of all students in lecture, and personally contact the ones missing (apart from the whole thing a not so good idea,)

You may want to have the students collectively create a cheat sheet that can be copied and distributed, It does cost a little class time but the standardized cheat sheet can be reused in subsequent classes, I was in a physics class that did this and I still use that cheat sheet 10 years later.

@ILiketoCode I'm back (safe and sound) and have answered. :)

In my studies I had once an exam where we were allowed to use any material we wanted. And I wrote this exam much worse than I actually could. The reason was that I never had such type of exam before and I was checking against the reference material all the time. This resulted in me simply running out of time. The lesson for me was that passing a new "type" or "style" of exam is a separate skill, which a student should acquire. And the less variation exams have in their structure the more systematically they actually check the knowledge.

As someone whose handwriting is both quiet large AND a mess: please please please don't force me to work at least an additional day, in the middle of exam-times, just to get those letters onto a piece of paper BY HAND. (I have recently been told that my handwriting comes with "encryption included"...)

This is what I did as a student (a long time ago). I would always prepare a cheat sheet as if it was something I was going to smuggle into an exam room. It didn't matter that I then left it at home; I was generally able to memorize its contents, and scribble it all down again at the beginning of the exam.

For this time only, allow the students to use 2 cheatsheets: their own, handwritten, and yours, printed with what you expect from a cheatsheet.

Many years ago, I took a semiconductor materials class. The instructor's policy was "open book, open notes, open ANYTHING YOU WANT except another person". It didn't help. You either KNEW the material, and only needed a few reference constants, or you didn't know it, and no amount of perfect reference material was going to help you. I loved that class!

It's 2017. Handwriting is a skill of vanishing usefulness. Doodling at most. Asking to prepare anything in handwriting is unreasonable unless the class is calligraphy.