Professors love to assign reading. Hundreds of pages of the stuff! And they expect you to do more than just read all of those words--you have to think and have ideas about them. Have class discussions... write long papers... it can be exasperating.
A good way to keep track of all that reading is by using a reading journal to write questions about things you understand, and to paraphrase the material you think is most important. This kind of "active reading" is like having a conversation with the text, and it begins by marking the text itself in ways that will highlight the ideas you want to return to later. You can underline key passages, circle points you have a comment or question about, even use colored pens or a "?" or "!" in the margins so you can find things later. Some people call this "annotation"--it's a kind of intellectual graffiti.
After you're finished marking the text, in your reading journal you might:
--paraphrase (try to write in your own words) the key passages;
--write comments about the circled passages;
--write out any questions you have about circled passages and then try writing answers to those questions. You don't kneed to know the answers--your thoughts on what they might be will be useful for discussion in class or in a later paper;
--Spend five or ten minutes freewriting about what you read. Begin with something that interests you from your notes, and write out any and all thoughts or connections you can think of. This often helps readers discover what makes the text tough to read, or what their own opinions are about the topic;
--You can even read through your own journal writing when you're finished and do some active reading on yourself by underlining your own best thoughts or points you'd like to further develop.
And presto! You have notes on the text and your responses to it. You'll have smart stuff to say in class, and when it comes time to write your next paper, much of the preliminary work of looking back over the reading will already be done. You'll be ready to get writing.