The Framework for K‐12 science education (The Framework) and Next Generation Science Standards (NGSS) emphasize the usefulness of learning progressions in helping align curriculum, instruction, and assessment to organize the learning process. The Framework defines three dimensions of science as the basis of theoretical learning progressions described in the document and used to develop NGSS. The three dimensions include disciplinary core ideas, scientific and engineering practices, and crosscutting concepts. The Framework defines three‐dimensional learning (3D learning) as integrating scientific and engineering practices, crosscutting concepts, and disciplinary core ideas to make sense of phenomena. Three‐dimensional learning leads to the development of a deep, useable understanding of big ideas that students can apply to explain phenomena and solve real‐life problems. While the Framework describes the theoretical basis of 3D learning, and NGSS outlines possible theoretical learning progressions for the three dimensions across grades, we currently have very limited empirical evidence to show that a learning progression for 3D learning can be developed and validated in practice. In this paper, we demonstrate the feasibility of developing a 3D learning progression (3D LP) supported by qualitative and quantitative validity evidence. We first present a hypothetical 3D LP aligned to a previously designed NGSS‐based curriculum. We further present multiple sources of validity evidence for the hypothetical 3D LP, including interview analysis and item response theory (IRT) analysis to show validity evidence for the 3D LP. Finally, we demonstrate the feasibility of using the assessment tool designed to probe levels of the 3D LP for assigning 3D LP levels to individual student answers, which is essential for the practical applicability of any LP. This work demonstrates the usefulness of validated 3D LP for organizing the learning process in the NGSS classroom, which is essential for the successful implementation of NGSS.

We have developed an integrated spectroscopy system combining total internal reflection fluorescence microscopy imaging with confocal single-molecule fluorescence spectroscopy for two-dimensional interfaces. This spectroscopy approach is capable of both multiple molecules simultaneously sampling and in situ confocal fluorescence dynamics analyses of individual molecules of interest. We have demonstrated the calibration with fluorescent microspheres, and carried out single-molecule spectroscopy measurements. This integrated single-molecule spectroscopy is powerful in studies of single molecule dynamics at interfaces of biological and chemical systems.

The Next-Generation Science Standards (NGSS) call for a different approach to learning science. They promote three-dimensional (3D) learning that blends disciplinary core ideas, crosscutting concepts and scientific practices. In this study, we examined explanations constructed by secondary science teacher candidates (TCs) as a scientific practice outlined in the NGSS necessary for supporting students' learning of science in this 3D way. We examined TCs' ability to give explanations that include explicit statements of underlying reasons for natural phenomena, as opposed to simply describing patterns or laws. In their methods courses, TCs were taught to organize explanations into a what/how/why framework, where what refers to what happens in specific cases (data or observations); how refers to how things usually happen and is equivalent to patterns or laws; and why refers to causal explanations or models. We examined TCs' ability to do this spontaneously and in a resource-rich environment as a first step in gauging their preparedness for NGSS-aligned teaching. We found that (1) the ability of TCs to articulate complete and accurate causal scientific explanations for phenomena exists along a continuum; (2) TCs in our sample whose explanations fell on the upper end of this continuum were more likely to provide complete and accurate explanations even in the absence of support from explicit standards; and (3) teacher candidate's ability to construct complete and accurate explanations did not correlate with Electronic supplementary material The online version of this article (

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Background Blended mathematical sensemaking in science (“Math-Sci sensemaking”) involves deep conceptual understanding of quantitative relationships describing scientific phenomena and has been studied in various disciplines. However, no unified characterization of blended Math-Sci sensemaking exists. Results We developed a theoretical cognitive model for blended Math-Sci sensemaking grounded in prior work. The model contains three broad levels representing increasingly sophisticated ways of engaging in blended Math-Sci sensemaking: (1) developing qualitative relationships among relevant variables in mathematical equations describing a phenomenon (“qualitative level”); (2) developing mathematical relationships among these variables (“quantitative level”); and (3) explaining how the mathematical operations used in the formula relate to the phenomenon (“conceptual level”). Each level contains three sublevels. We used PhET simulations to design dynamic assessment scenarios in various disciplines to test the model. We used these assessments to interview undergraduate students with a wide range of Math skills. Interview analysis provided validity evidence for the categories and preliminary evidence for the ordering of the categories comprising the cognitive model. It also revealed that students tend to perform at the same level across different disciplinary contexts, suggesting that blended Math-Sci sensemaking is a distinct cognitive construct, independent of specific disciplinary context. Conclusion This paper presents a first-ever published validated cognitive model describing proficiency in blended Math-Sci sensemaking which can guide instruction, curriculum, and assessment development.