Mathematical reasoning skills are a desired outcome of many introductory physics courses, particularly calculus-based physics courses. Positive and negative quantities are ubiquitous in physics, and the sign carries important and varied meanings. Novices can struggle to understand the many roles signed numbers play in physics contexts, and recent evidence shows that unresolved struggle can carry over to subsequent physics courses. The mathematics education research literature documents the cognitive challenge of conceptualizing negative numbers as mathematical objects-both for experts, historically, and for novices as they learn. We contribute to the small but growing body of research in physics contexts that examines student reasoning about signed quantities and reasoning about the use and interpretation of signs in mathematical models. In this paper we present a framework for categorizing various meanings and interpretations of the negative sign in physics contexts, inspired by established work in algebra contexts from the mathematics education research community. Such a framework can support innovation that can catalyze deeper mathematical conceptualizations of signed quantities in the introductory courses and beyond.

Relating two quantities to describe a physical system or process is at the heart of "doing physics" for novices and experts alike. In this paper, we explore the ways in which experts use covariational reasoning when solving introductory physics graphing problems. Here, graduate students are considered experts for the introductory level material, as they often take the role of instructor at large research universities. Drawing on work from Research in Undergraduate Mathematics Education (RUME), we replicated a study of mathematics experts' covariational reasoning done by Hobson and Moore with physics experts [N. L. F. Hobson and K. C. Moore, in RUME Conference Proceedings, pp. 664-672 (2017)]. We conducted think-aloud interviews with 10 physics graduate students using tasks minimally adapted from the mathematics study. Adaptations were made solely for the purpose of participant understanding of the question, and validated by preliminary interviews. Preliminary findings suggest physics experts approach covariational reasoning problems significantly differently than mathematics experts. In particular, two behaviors are identified in the reasoning of expert physicists that were not seen in the mathematics study. We introduce these two behaviors, which we call Using Compiled Relationships and Neighborhood Analysis, and articulate their differences from the behaviors articulated by Hobson and Moore. Finally, we share implications for instruction and questions for further research.

One desired outcome of introductory physics instruction is that students will be able to reason mathematically about physical phenomena. Little research has been done regarding how students develop the knowledge and skills needed to reason productively about physics quantities, which is different from either conceptual understanding or problem-solving abilities. We introduce the Physics Inventory of Quantitative Literacy (PIQL) as a tool for measuring quantitative literacy (i.e., mathematical reasoning) in the context of introductory physics. We present the development of the PIQL and results showing its validity for use in calculus-based introductory physics courses. As has been the case with many inventories in physics education, we expect large-scale use of the PIQL to catalyze the development of instructional materials and strategies-in this case, designed to meet the course objective that all students become quantitatively literate in introductory physics. Unlike concept inventories, the PIQL is a reasoning inventory, and can be used to assess reasoning over the span of students' instruction in introductory physics.

Mathematical reasoning skills are a desired outcome of introductory physics courses, particularly calculusbased courses. Signed quantities are ubiquitous in physics, and sign carries important and varied meanings. Unlike physics experts, novices struggle with the many roles signed numbers can play in physics contexts; recent evidence shows that unresolved struggle carries over to subsequent physics courses. Mathematics education research literature documents cognitive challenges of conceptualizing negative numbers as mathematical objects-for experts, historically, and for novices as they learn. We add to the small but growing body of physics education research that focuses on student reasoning about signed quantities and the role of the negative sign in models. This paper contributes a framework for categorizing the various natures of the negative sign in physics contexts, modeled on the established natures of negativity in algebra from the mathematics education research community. We hope such a framework can facilitate innovation in methods and curricular activities to catalyze a deeper mathematical conceptualization of signed quantities in the introductory courses and beyond.

The Physics Inventory of Quantitative Literacy (PIQL), a reasoning inventory under development, aims to assess students' physics quantitative literacy at the introductory level. The PIQL's design presents the challenge of isolating types of mathematical reasoning that are independent of each other in physics questions. In its current form, the PIQL spans three principle reasoning subdomains previously identified in mathematics and physics education research: ratios and proportions, covariation, and signed (negative) quantities. An important psychometric objective is to test the orthogonality of these three reasoning subdomains. We present results from exploratory factor analysis, confirmatory factor analysis, and module analysis that inform interpretations of the underlying structure of the PIQL from a student viewpoint, emphasizing ways in which these results agree and disagree with expert categorization. In addition to informing the development of existing and new PIQL assessment items, these results are also providing exciting insights into students' quantitative reasoning at the introductory level. arXiv:1907.05491v2 [physics.ed-ph]