Teachers' mathematical knowledge has important consequences for the quality of the learning environment they create for their students to learn mathematics. Yet relatively little is known about how teachers reason proportionally, despite the fact that proportional reasoning is foundational for several mathematics concepts and that ratios and…

This study examines the collective mathematical reasoning when students and teachers in grades 3, 4, and 5 explore fractions derived from length comparisons, in a task inspired by the Elkonin and Davydov curriculum. The analysis showed that the mathematical reasoning was mainly anchored in mathematical properties related to fractional or algebraic…

Background: Key to optimizing Computational Thinking (CT) instruction is a precise understanding of the underlying cognitive skills. Román-González et al. (2017) reported unique contributions of spatial abilities and reasoning, whereas arithmetic was not significantly related to CT. Disentangling the influence of spatial and numerical skills on CT…

The purpose of this research study was to learn about students' conceptions concerning the line of best fit just prior to their introduction to the topic. Task-based interviews were conducted with thirty-three students, focused on five tasks that asked them to place the line of best fit on a scatterplot and explain their reasoning throughout the…

Linear functions are an important part of the middle school mathematics curriculum. Students in the middle grades gain fluency by working with linear functions in a variety of representations (NCTM 2001). Presented in this article is an activity that was used with five eighth-grade classes at three different schools. The activity contains 15 cards…

The Common Core State Standards emphasize students writing analytically in response to texts. Questions remain about the nature of instruction that develops students' text-based writing skills. In the present study, we examined the role that writing task quality plays in students' mastery of analytic text-based writing. Text-based writing tasks…

The aims of this study were to investigate how upper-elementary-grade students compare the volume of rectangular prisms of equal volume (specifically, students' noticing and reasoning for invariance of volume and coordination of the three linear dimensions of rectangular prisms) and how students' levels of sophistication in volume measurement…

Findings from an on-going design experiment within a year-long graduate course for middle school teachers of mathematics are reported. The purpose of the course was to help teachers assist students in transitioning from arithmetic to algebraic reasoning. Goals included developing teachers' ability to interpret, compare, and generalize across…