What do people in general prefer, reading on a screen or reading on paper? The matter is not settled. There have been numerous investigations and researches about that matter, but none of them can come with a decisive answer.
Most studies before 1992 showed that one reads less accurately and more slowly on screens, but we cannot really compare the pixels of the screens in 1992 to the high definition retina screens we have nowadays.
But then other studies since 1992 cannot really come to a consensus and show inconsistent results. The majority however comes to the same result as the studies before 1992: reading from a screen leads to more mistakes. Recent surveys by scientificamerican.com also show that people still prefer paper, but only consider iPads and e-readers because of their practicality. Most people like the tactile aspect of a book, they like the smell of it, they like how it looks and feels.
The difference between reading on screens and reading on paper is a psychological and physiological matter. It depends on how the brain interprets written language. The brain sees a text as a tactile part of the world, and sees letters and words as physical objects, since it has no other way to interpret them. We actually are not born with brains that want or can read, it requires a lot of training. People did not read or write in the biggest part of the existence of mankind, so it is actually a rather new part of our lives. Still today it seems like the most normal thing, and if you cannot read or write nowadays in our western society you are considered a pariah or an outcast.
Certain regions in the brain are specialised for object recognition, and if one is always used to reading on paper, one’s brain might have difficulties in dealing with reading on screens, because it might not immediately recognise the screen as something that people read from.
There is also a geographical or topographical issue concerning reading on screens or reading on paper. In a book we have a left page and a right page, which leads to a clear orientation. On screens there is no such thing, only a scrollbar that shows you how far you have got.
Reading on screens inhibits people from mapping a journey in their minds. It is harder to see one passage in the context of the entire text.
The fact that there is little conclusive material about this matter leads to the fact that we still have to be careful with reading on screens. If you want your pupils to see the bigger picture and to get the context, which is very important in reading skills, you should find a healthy mix of reading on screen and on paper, giving the benefit of the doubt to paper. Working in class can come in handy on a screen, but for studying or cramming, reading on paper might be the safer way out.