There are a number of advantages of a lesson plan both internally and externally. Internally, by using a lesson plan a teacher will have both a framework and a guideline for teaching activities (Brown, 2001). By using this guideline, the teachers will at least know what kind of activity that they will ask their students to do and how long each activity should last. At the end of the lesson, teachers should have an expectation of what their students should accomplish, and lesson plan is a guide that will assists them to realize such expectation. In other words, a lesson plan may function as a proposal for action in classroom teaching and learning process (Harmer, 2007b). Hence, the teaching and learning process should be optimized. So, it can be concluded that lesson plan for internal reasons may give teacher more confidence to learn the subject matter better, to enable lessons to run more smoothly, and to anticipate problems before they happen.
Further, the lesson plans also are useful outside the classroom in three ways (Farrel, 2002). First, it helps teachers to consider the content, materials, the sequences, timing, and activities. Thus, it is easier to carry out learning and students will find it helpful and easy to learn. Second, it gives teachers time to see a list of contents and consider what material to be delivered. It means that learning plan is developed according to the needs and characteristics of learners, school, and subject. Moreover, these content and