Investigations in Mathematics Learning Official Journal of The Research Council on Mathematics Learning TABLE OF CONTENTS Volume 7, Number 1 - - Fall 2014 Redefining the Whole: Common Errors in Elementary Preservice Teachers’ Self-Authored Word Problems for Fraction Subtraction . . . . . . . . . . . . . . . . . . . . . . . . . 1-22 Juli K. Dixon, University of Central Florida Janet B. Andreasen, University of Central Florida Cheryl L. Avila, University of Central Florida Zyad Bawatneh, University of Central Florida Deana L. Deichert, Montgomery County Community College Tashana D. Howse, Daytona State College Mercedes Sotillo Turner, University of Central Florida Abstract A goal of this study was to examine elementary preservice teachers’ (PSTs) ability to contextualize and decontextualize fraction subtraction by asking them to write word problems to represent fraction subtraction expressions and to choose prewritten word problems to support given fraction subtraction expressions. Three themes emerged from the data: (1) subtraction problems were represented by an incorrect redefinition of the whole; (b) the type of unit chosen for the whole (e.g. cups, gallons, pounds vs. pizzas, pies) influenced the success of PSTs in representing Separate (Result Unknown) context problems for subtraction; and (c) the structure of the problem influences PSTs’ performance in writing subtraction word problems. Responsive Decision Making from the Inside Out: Teaching Base Ten to Young Children . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-53 Susan B. Empson, The University of Texas at Austin Abstract Decision making during instruction that is responsive to children’s mathematical thinking is examined reflexively by the researcher in the context of teaching second graders. Focus is on exploring how the research base on learning informs teaching decisions that are oriented to building on children’s sound conceptions. The development of four children’s understanding of base ten over a ten-week period is tracked. “The work of teaching orients teachers to constantly consider their next move” (Jacobs, Lamb, Philipp, & Schapelle, 2011, p. 98) Investigations in Mathematics Learning Official Journal of The Research Council on Mathematics Learning Second-Graders’ Mathematical Practices for Solving Fraction Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54-81 Patricia S. Moyer-Packenham, Utah State University Johnna J. Bolyard, West Virgiia University Stephen I. Tucker, Utah State University Abstract Recently, over 40 states in the United States adopted the Common Core State Standards for Mathematics (CCSSM) which include standards for content and eight standards for mathematical practices. The purpose of this study was to better understand the nature of young children’s mathematical practices through an exploratory examination of the practices of a group of second-grade students engaged in several mathematical tasks focused on rational number concepts. Twenty-five second-grade students completed three fraction tasks in structured clinical interviews. The interviews and student work were analyzed using an interpretational analysis to examine the data for constructs, themes, and patterns that were useful in explaining children’s mathematical practices. The results reveal that children used a variety of mathematical practices during the interviews to respond to the mathematical problems presented. Children’s mathematical practices were both a product that they used to solve the mathematical situations, and a process that was developing during the interactions of the interview. The findings lead to new insights about how mathematical practices develop and what promotes their development.