Conventions of content-area books are the books used to supplement and facilitate successful understanding of the content area. Convention books expounds on the content are so that the learners can adequately comprehend the basic concepts required in that specific area. It has been revealed that, content-area textbooks are quite useful as they help learners to reinforce what they have been taught by their teachers at their own pace. In this case, the teacher guides learners in choosing the most useful books for the learners in order to enhance better understanding of the content area. If content area books are not used appropriately, some of the learners may not understand the intended concepts in the content area, as the teacher may not cover all the concepts required in a single lesson. On this basis therefore frequent and careful use of content-area books determine a lot in enhancing learners’ comprehensibility of the content area.