We describe efforts toward the development of a hypothetical learning progression (HLP) for the growth of grade 7-14 students' models of the structure, behavior and properties of matter, as it relates to nanoscale science and engineering (NSE). This multi-dimensional HLP, based on empirical research and standards documents, describes how students need to incorporate and connect ideas within and across their models of atomic structure, the electrical forces that govern interactions at the nano-, molecular, and atomic scales, and information in the Periodic Table to explain a broad range of phenomena. We developed a progression from empirical data that characterizes how students currently develop their knowledge as part of the development and refinement of the HLP. We find that most students are currently at low levels in the progression, and do not perceive the connections across strands in the progression that are important for conceptual understanding. We suggest potential instructional strategies that may help students build organized and integrated knowledge structures to consolidate their understanding, ready them for new ideas in science, and help them construct understanding of emerging disciplines such as NSE, as well as traditional science disciplines. Recent scientific research has revealed that matter exhibits novel, often unexpected properties as it transitions between the bulk form and that of individual atoms and molecules. This transition generally occurs at the nanoscale, where at least one dimension measures between 10 À9 and 10 À7 m. Scientists and policy-makers predict that the new information and technologies resulting from nanoscale science and engineering (NSE) research will have extensive societal implications that may be realized in a broad range of areas, including health care, agriculture, food, water purification, and energy and environmental concerns (PCAST, 2005). These predictions have created a need to incorporate ideas related to NSE into the science curriculum.A foundation for NSE literacy must include a robust model of the nature of matter, which includes the structure of matter, how it behaves and interacts, as well as its properties and what determines those properties. These ideas are also the foundation of understanding chemistry and are considered important aspects of science literacy (American Association for the Advancement of Science [AAAS], 1993; National Research Council [NRC], 1996). Due to the extensive nature of the science content, we will focus on only a portion of it in this manuscript. We describe our efforts toward the development of a hypothetical learning progression (HLP) that characterizes a path along which grade 7-14 students may develop more sophisticated models of atomic structure, and the electrical forces that govern interactions at the nano-, molecular, and atomic scales. Each of these knowledge domains represents a significant portion of one or more big ideas of NSE (Stevens, Sutherland, & Krajcik, in press). We followed an iterative, desi...

This paper presents an integrative framework for analyzing science meaning‐making with representations. It integrates the research on multiple representations and multimodal representations by identifying and leveraging the differences in their units of analysis in two dimensions: timescale and compositional grain size. Timescale considers the duration of time a learner typically spends on one or more representations. Compositional grain size refers to the elements of interest within a representation, ranging from components such as visual elements, words, or symbols, to a representation as a whole. Research on multiple representations focuses on the practice of re‐representing science concepts through different representations and is typically of long timescale and large grain size. Research on multimodal representations tends to consider how learners integrate the components of a representation to produce meaning; it is usually of finer grain size and shorter timescale. In the integrative framework, each type of analysis on multiple and multimodal representations plays a mutually complementary role in illuminating students’ learning with representations. The framework is illustrated through the analysis of instructional episodes of middle school students using representations to learn nanoscience concepts over the course of a lesson unit. Finally, recommendations for new research directions stemming from this framework are presented.

Reform efforts have emphasized the need to support teachers' learning about reform-oriented practices. Educative curriculum materials are one potential vehicle for promoting teacher learning about these practices. Educative curriculum materials include supports that are intended to promote both student and teacher learning. However, little is known about the extent to which existing curriculum materials provide support for teachers and the ways they can be improved. In this study, eight sets of high school biology curriculum materials were reviewed to determine their potential for promoting teacher learning. Design heuristics for educative curriculum materials were adapted for use as evaluation criteria. From this analysis, several themes emerged. First, the materials tended to provide support for teachers' subject matter knowledge and pedagogical content knowledge for students' ideas (e.g., misconceptions) but rarely for their pedagogical content knowledge of scientific inquiry. Second, the materials contained several implementation guidance supports but far fewer rationales for instructional decisions, which are an important feature of educative curriculum materials. Finally, the quality of support varied widely, differing in its degree of relevance, pedagogical helpfulness, and depth. The article concludes with recommendations for the redesign of existing curriculum materials. ß

Size and scale is a "big idea" in nanoscale science and engineering and is poorly understood by secondary students. This paper describes the design process, implementation, and evaluation of a 12-h instructional unit for size and scale, in a summer science camp for middle school students from a low SES public school district. Instructional activities were designed following a construct-centered design approach and included the use of microscopes, custom-made computer simulations, and 2-D and 3-D scale models. The unit followed a project-based instructional approach and was contextualized with the driving question, "How can nanotechnology keep me from getting sick?" Pre-and post-intervention interviews revealed that students significantly increased their qualitative and quantitative knowledge of the size of objects including atom, viruses, and cells, with an effect size of 0.8 for an overall metric. The campers closed the gap with private middle school students and on some measures surpassed high school students from the same district. The principle of "broad spectrum" curriculum and instruction -activities that target specific advanced understandings but simultaneously scaffold or support the learning of more fundamental, prerequisite ideaswas inductively generated from an analysis of the learning activities.

Global carbon cycling describes the movement of carbon through atmosphere, biosphere, geosphere, and hydrosphere; it lies at the heart of climate change and sustainability. To understand the global carbon cycle, students will require interdisciplinary knowledge. While standards documents in science education have long promoted interdisciplinary understanding, our current science education system is still oriented toward single-discipline-based learning. Furthermore, there is limited work on interdisciplinary assessment. This article presents the validated Interdisciplinary Science Assessment of Carbon Cycling (ISACC), and reports empirical results of a study of high school and undergraduate students, including an analysis of the relationship between interdisciplinary items and disciplinary items. Many-faceted Rasch analysis produced detailed information about the relative difficulty of items and estimates of ability levels of students. One-way ANCOVA was used to analyze differences among three grade levels: high school, college Freshman-Sophomore, college Junior-Senior, with number of science courses as a covariate. Findings indicated significantly higher levels of interdisciplinary understanding among the Freshman-Sophomore group compared to high school students. There was no statistically significant difference between Freshman-Sophomore group and Junior-Senior group. Items assessing interdisciplinary understanding were more difficult than items assessing disciplinary understanding of global carbon cycling; however, interdisciplinary and disciplinary understanding were strongly correlated. This study highlights the importance of interdisciplinary understanding in learning carbon cycling and discusses its potential impacts on science curriculum and teaching practices. K E Y W O R D S global carbon cycling, interdisciplinary assessment, interdisciplinary learning, interdisciplinary understanding, Rasch analysis