Skimming a book's visual density predicts how it should be read
You should skim a textbook by looking at every page in order to get a brief idea of the text-to-image ratio, how long the chapter is, whether there are diagrams/charts, and if anything jumps out at you.
Matt DiMaio Skimming for exposure will increase later comprehension Reading a textbook front to back like a novel fails to retain it Classical Pedagogy
Declarative Knowledge American "New Math" Reform