My wife and I went to a movie. It took me a long time to figure out what was happening until they did some flashbacks. I felt very lost just jumping into the middle of the movie. Where do you begin your unit planning? Do you start in deciding on the standard, the particular aspect and then the learning goal? Or do you jump right into the activities you will do in the unit?
Understanding by Design advocates starting with the standard, the assessment, and then the activity so that “the end is always in mind”. Without a firm view of your “end” you will not be able to measure student learning against the standard. f you plan “in medias res”, you cannot be sure if you activities truly help the student reach the learning goal. Also, you may not be focusing on the essential ideas for the standard but, instead, on some very minor learning. Likewise, with a firm view of the “end” learning, you may focus on students’ minor errors that are not the most serious errors.
The preplanning (standard and assessment) for the lesson gives a foundation for all you do in the unit. Start from the beginning so your students can arrive at the end.
For any one who is interested in implementing formative assessment in the classroom, my book,
Formative Assessment: Responding to Students is available through Eye-on-Education.
Education with Technology Harry G. Tuttle 
