Read text books like you would a magazine or newspaper. (They are not novels.)
Start by skimming.
• Read the subject headings
• Look at the images and read the image captions
• Read the introduction and summary to each Chapter
Go back and read the text itself.
• Read the introductions and summaries to each subject area
• Look at the sections that most interest you
Take notes while you are reading (reference with page numbers), highlight sections or flag pages that interest you.