My first recommendation to you would be the
11-inch iPad Pro or a
10-inch iPad Air, or even an
ordinary 10-inch iPad, and to highlight your PDF files there. Or a
10-inch Samsung S8 tablet. (Each of these is neither too big, nor too small.)
The best PDF app to do that, unfortunately, would likely be Adobe Acrobat. Yes, it's dumb corporate software, but other options turned out to be unreliable for me. GoodReader for iOS is great, but messes up syncing with Dropbox. (And you really should back up your annotations all the time, because they can disappear from a PDF file any minute!) Another good iOS PDF app is PDF Expert.
And yes, many teachers are dumb as well, unfortunately, especially when it comes to using today's technology. Many teachers still mentally live somewhere in the 1970s. (And you can believe me, because a large school has been among my clients for the last 21 years; I can see that some folks' computer skills in that school today are the same as they were back in 2001, which is to say: pretty much non-existent.)
Nowhere does the failure of our education system present itself more clearly than in this: that many teachers and scientists, even as late as in 2022, believe PDF to be the primary format of distribution of digital literature, although, as correctly observed by our fellow posters above, PDFs should ideally be used for
printing and nothing else (while printing itself should ideally
never be used).
The folks who are supposed to lead us to enlightened tomorrows (teachers and scientists) are frequently the dumbest of all people in certain aspects.
Oh my! Where is our civilization headed!
Since you seem to be rejecting traditional tablets, my second recommendation to you would be the 10-inch e-ink
Onyx Boox Air 2 Plus. (Beware: Air 2
Plus is the current model with a larger battery, not just Air 2.) The cost is around 500 dollars/euros, comparable to a similar-sized iPad Air. Preferably, buy this via Amazon, not directly through Onyx (because depending on your location, you might have additional import taxes and duties to pay).
PS: I disagree you need at least a 10-inch screen to read/highlight PDF files. I've been doing that for many years on the 8-inch iPad minis, for example, with no problem whatsoever. It's not comfortable, but then, a rigid format like PDF is
never comfortable. Only an EPUB file is a true e-(text)book – if only our teachers and scientists had any idea!
In emergency situations, I've even been able to read and highlight PDF files on my 6-inch Samsung Note phone, too – again, with no bigger issues or consequences for my eyesight.
Also, I've never ever used a stylus for anything – never even bother to pull out Samsung's S Pen from its receptacle inside my phones; I agree with Steve Jobs on this if not on much else: that you don't need a stylus because you already carry 10 styluses around with you at all times on your hands.
