Your aim is to reduce the amount of verbiage you're trying to remember for a test. Rather use the key words which will usually be the nouns and verbs. Aim to mark the major idea in each paragraph. Distinguish between definitions and examples. Both are important.
Some students like to circle important concepts, ideas , or subheadings.
Other students prefer a box. Read the text. Then apply the information to the figures, graphs or example problems. It's important to spend some time reviewing the material you have just finished reading. Review the subheadings and recall the main points This is an excellent strategy because you are forcing yourself to recite the major points without looking at your underlining.