Once you have finished your plans, you will find that your class runs much smoother than it would without it. For example, your students will enjoy the luxury of the daily routine and the security of knowing that their teacher will know exactly what the plan is on a day to day basis. Should a delay occur, such as a classroom discussion tangent or a school cancellation, you will nevertheless have enough time to reschedule various events. Writing plans are also useful in that if you plan to take any field trips, you will be able to prepare for these events ahead of time.
A list of objectives can help you to gauge whether or not your students have achieved everything they should have once the lesson is over. Depending on the subject matter, objectives might be practical, for example, what can the student do at lesson completion. The objectives could also be knowledge based, for example, what does the student know after the lesson is complete.