Measurement can develop in the earliest years from children's experience, and it readily lends itself to real-world application. Focusing on research and practice, NCTM's 2003 Yearbook presents current thinking about the learning and teaching of measurement, including students' understanding, the mathematics of measurement, estimation and approximation, connections, and pedagogy. The 331-page yearbook divides into two parts and twenty-four chapters, as follows. Part 1: "Elementary School," contains: Introduction (Michelle Stephan and JoAnne Mendiola); (1) Linear, Area, and Time Measurement in Prekindergarten to Grade 2 (Michelle Stephan and Douglas H. Clements); (2) Understanding Children's Developing Strategies and Concepts for Length (Jeffrey E. Barrett; Graham Jones; Carol Thornton; Sandra Dickson); (3) Making Connections with Powerful Ideas in the Measurement of Length (Nicola Yelland); (4) Developing the Building Blocks of Measurement with Young Children (Theresa J. Grant and Kate Kline); (5) Benchmarks as Tools for Developing Measurement Sense (Elana Joram); (6) Assessing and Developing Measurement with Young Children (Doug Clarke; Jill Cheeseman; Andrea McDonough; and Barbara Clark); (7) Count Me into Measurement: A Program for the Early Elementary School (Lynne Outhred; Michael Mitchelmore; Diane McPhail; and Peter Gould; (8) Developing an Understanding of Measurement in the Elementary Grades (Richard Lehrer; Linda Jaslow; and Carmen L. Curtis); (9) Understanding Students' Thinking about Area and Volume Measurement (Michael T. Battista); (10) Structuring a Rectangle: Teachers Write to Learn about Their Students' Thinking (Deborah Schifter and Janice Szymaszek); (11) About Students' Understanding and Learning the Concept of Surface Area (Cinzia Bonotto); (12) The Measurement of Time: Transitivity, Unit Iteration, and Conservation of Speed (Constance K. Kamii and Kathy Long); and (13) Bridging Yup'ik Ways of Measuring to Western Mathematics (Jerry Lipka; Tod Shockey; and Barbara Adams). Part 2: "Secondary School," contains: Introduction (Veronica Meeks and Robert F. Wheeler); (14) What Students Know about Measurement: Perspectives from the NAEP (Marilyn E. Strutchens; W. Gary Martin; and Patricia Ann Kenney); (15) Providing Opportunities for Students and Teachers to "Measure Up" (Melissa Boston and Margaret Smith); (16) Measuring Montana: An Episode in Estimation (Ted Hodgson; Linda Simonsen; Jennifer Lubek; and Lyle Anderson); (17) Estimation at Work (Thomasenia Lott Adams; and Gregory Harrell); (18) Exploring Measurement Concepts through Literature: Natural Links across Disciplines (Richard Austin; Denisse Thompson; and Charlene Beckmann); (19) Using the Geoboard to Enhance Measurement Instruction in the Secondary School Mathematics Classroom (Barbara A. Burns and Gail A. Brade); (20) Using Measurement to Develop Mathematical Reasoning at the Middle and High School Levels (Mary C. Enderson); (21) Is Our Teaching Measuring Up? Race-, SES-, and Gender-Related Gaps in Measurement Achievement (Sarah T. Lubienski); (22) Measurement, Representation, and Computer Models of Motion (Christopher Hartmann and Jeffrey Choppin); (23) Measuring the Unmeasurable: Using Technology to Study the Irrational (Maurice Burke); and (24) Measurement in Adult Education: Starting with Students' Understandings (Myriam Steinback; Mary Jane Schmitt; Martha Merson; and Esther Leonelli). The 77-page companion booklet, which not only illustrates some of the issues from the yearbook but also contains activities that go beyond the content, contains teaching notes and ready-to-use handouts. The booklet contains the following eighteen chapters: (1) A Word to Teachers; (2) Woolly Worms (Andrea McDonough; Jill Cheeseman; and Doug Clarke); (3) Teddy Counters (Andrea McDonough; Jill Cheeseman; and Doug Clarke); (4) Broken Rulers (Jeffrey Barnett and Sandra Dickson); (5) Benchmarks for Measurement Units (Elana Joram); (6) Measuring Volume Informally (Sinan Olkun); (7) Angle Measurements (George W. Bright); (8) Estimation (George W. Bright); (9) Greatest Perimeter (George W. Bright); (10) Measuring the Mountain State (Ted Hodgson); (11) Area of Kite: Teaching Notes (George W. Bright); (12) Making Rabbit Pens (Margaret S. Smith and Melissa Boston); (13) The Perimeter and Area of Similar Figures (Barbara A. Burns and Gail Brade); (14) Ratios--Surface Areas and Volumes (George W. Bright); (15) Look-Alike Rectangles (Suzanne Levin Weinberg); (16) Perimeter and Area of Similar Figures (Mary C. Enderson); (17) Determining Densities of Various Kinds of Wood (Joseph I. Stepans); and (18) Investigating Densities of Different Paper Materials (Joseph I. Stepans).