And rewind, too. But that is cumbersome compared to just staring at the last few lines of text or the last few formulas, or even paging back for some earlier stuff which the last few lines are based on/refer back to.

When learning, I even prefer books to the internet, despite the advantage of Googling stuff needed.

This all may depend on what you are learning, though. (I was educated as physicist and astronomer -- lots of formulas to use, understand and connect to each other.)

_{*Lunatic*, n.
One whose delusions are out of fashion.}