You are correct–more and more is added to the list that teachers are expected to do with and for students, and unfortunately some of it is not directly related to the standards you are expected to help students master. However, if you do not engage students at the beginning of the lesson and preview vocabulary as needed, you will not be ensured that your students will be ready to learn when you begin teaching new content. It takes a lot more time to go back, undo misconceptions, and reteach than it does to be certain that your students are ready to learn.