I would really like a way to stamp a student’s individual slide in their Google Slides as complete. It could be an image or a watermark but the key is that the student cannot copy the “stamp” to use in their other slides. Is that even possible?
I don’t think so, but you can copy it over to your own personal copy of their presentation (which would only have the complete slides that you manually copy).
I guess you get the same effect if you personally own the “master” copy of every presentation, that they can view but not edit. For every new slide they get assigned, they submit it in their own presentation, but it doesn’t count until it’s moved over to the master copy as complete (and presumably final). Would that work?
Is this for grading purposes? Do you just need to keep track of which slides you’ve already seen, or?
If a slide has received full points I want to mark it so that the student knows it is complete and that I don’t have to look at it again. With Google Docs it is easy as only have to make a note in the margin.
I’m an idiot. Right-click in the margin pulls up comments. So I can do it like I do on Google Docs.
Awesome 
I wondered idly about that.
Most productivity suites incorporate aimilar review features across all the tools, so it makes sense that you’d be able to add comments to presentations as you would a spreadsheet or a document.
Unlike Docs, this one you have to know to get to it. But I’ve wondered that too. I guess I could have saved SD electrons by Google-searching “making comments google slides”
Well, your bringing the question here (and sharing the answer) was good for our learning, so I appreciate it.