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Measurement instruction has at least three distinct agendas. The first and most important is to help children understand what measurement is and how to go about doing it. This includes an understanding of the attribute that is being measured, how units are used in measuring, and an understanding of how measuring tools work. A second agenda is very much related to the first. It can be termed *measurement sense*; a familiarity of the most commonly used standard units, an ability to estimate with commonly used measures, and some flexibility with the use of related units. The third agenda is different from the first two: the development and use of a few standard formulas. Generally in the K-8 curriculum, these are area and volume formulas for common shapes.

Within the activities for this scheme there is considerable flexibility and need for decision-making. When, why, and for how long should informal units be used? How quickly do you progress? What is the role of estimation and how can that be built into the program? My goal when teaching this chapter is to help teachers appreciate this general framework and gain some perspective concerning these decisions. Helping teachers see this general plan is an efficient method of getting at all measurement in school. You will never be able to discuss the measurement of every attribute that is measured in the elementary school.

Most of us have a great deal more skill with length estimation, of both short and long distances, than we do with weight or capacity estimates. I suspect that we simply have done more length estimation in our everyday lives. The effect is that we have a much better measurement sense for length than most any other area. This fact seems like a strong argument for estimation.

A second idea concerning formulas is that they do represent an opportunity to engage children in some nice mathematics. This is a great place to help students see that when mathematical ideas are c related one to another, they are relatively easy to understand. In this section you will find a coordinated development of area and volume formulas that I do not believe is presented in other texts. Formulas for parallelograms (beginning with rectangles), triangles, trapezoids, circles, cylinders (including the special case of prisms), and cones (including the special case of pyramids) are all related to a single concept of the product of base times height. This sequence of formula development is a nice example of how conceptual big ideas connect mathematics.