Learning the main ideas in any text is essential. And its not just about learning what the author is talking about, but it’s also being able to understand it in your own words that is also critical. So, finding the main ideas is perfect for outlining in textbooks, especially when speed reading.
Try making a habit of finding the main idea/s in every paragraph that you read. Finding and extracting these details means that you zone in on the authors point more quickly, and therefore can understand the text rather than getting lost. You will find there is usually one important detail associated with every main point amongst the text. As you go along the more important facts that you find the easier it will be when you come to review them, as you will have made the connections between the ideas and the supporting facts.
When you first open a text to study/read there are a few questions that you should ask yourself: Why are you reading the text? Are you reading for a purpose or for pleasure? What do you wish to know after you have completed reading it? Identify your purpose of reading. Once your purpose has been identified, then you need to look at the text and decide whether it is going to meet your criteria. One of the easier ways to do this is to read the introduction and chapter headings. In the introduction you should be told at whom the text is aimed and what the text hopes to achieve. The chapter headings will give you an overall sense as to the structure of the text.
In the case of books, upon reading the introduction and chapter headings, question does the text meet what you are looking for. Is it going to answer your questions or is it something that is totally irrelevant? If you find that your questions are not met perhaps finding a different source would be a better idea.
In an article, skim through and identify the main idea. Learn where the article is heading, and question if this source is what you need or if another would be better. Read lightly and flexibly. If you need finer details slow down and read for that purpose, answering the questions that are most important. As most know very few words carry what the text means, therefore speed up to get past redundant or useless information.