The periodic review helps one maintain concentration, process information more deeply, and remember it longer. To illustrate, show students your text. Talk about what you marked and why, what cues you used to know these were important points. Then model how you review and summarize while you read, what you say to yourself during those pauses to review. Ask students in pairs to try the same thing with the next two sections, each taking a turn at identifying the main ideas and summarizing.
Active reading takes practice.
Acknowledge that students may feel awkward at first, but the more they read actively, the more skilled they will become. As they develop their skills, both their reading speed and comprehension will improve. They need to reread and then try again to summarize the main points. If they still cannot explain the ideas after two or three tries, tell them to formulate a question about the section, write it down, and bring it to class. Requiring that they submit questions on sections they do not understand discourages students from giving up too soon.