Comprehension requires focus, retention and reasoning. If a student has trouble focusing or remembering on an ongoing basis, it is important to put the appropriate supports in place to help students find ways to be aware of lapses, find strategies to address them, and gradually build stamina for longer reading periods. Using visual aids, speaking or other forms of reinforcement will be important in supporting a student's progress. Note that difficulties with working memory, which affect how you retain what you just read to make sense of a whole sentence or paragraph, are different from difficulties focusing on longer or less interesting texts which is often related to attention challenges. You can find strategies to address longer texts here.