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Within chemistry education, there are various curricular and pedagogical approaches that aim to improve teaching and learning in chemistry. Efforts to characterize these transformations have primarily focused on student reasoning and performance, and little work has been done to explore student perceptions of curricular and pedagogical transformations and whether these perceptions align with the transformational intent. To complement our previous work on the Organic Chemistry, Life, the Universe, and Everything (OCLUE) curriculum, we developed this exploratory study to determine if students had perceived the goals of the transformation. As in our previous research on OCLUE, we compared perceptions between OCLUE and a more traditional organic chemistry course. Using inductive and deductive qualitative methodologies, we analyzed student responses to three open-eneded questions focused on how students perceived they were expected to think, what they found most difficult, and how they perceived they were assessed. The findings were classified into three superodinate themes: one where students perceived they were expected to learn things as rote knowledge, such as memorization ("Rote Knowledge"), another where students perceived they were expected to use their knowledge ("Use of Knowledge"), and responses that used vague, generalized language, were uninformative, or did not address the questions asked ("Other"). Students in these two courses responded very differently to the open-ended questions with students in OCLUE being more likely to perceive they were expected to use their knowledge, while students in the traditional course reported rote learning or memorization more frequently. As the findings evolved, our interpretations and discussions were influenced by sociocultural perspectives and other cultural frameworks. We believe this approach can provide meaningful insights into transformational intent and certain features of classroom cultures.

Introductory courses are often designed to cover a range of topics with the intent to offer students exposure to the given discipline as preparation to further their study in the same or related disciplines. Unfortunately, students in these courses are often presented with an overwhelming amount of information that may not support their formation of a usable coherent network of knowledge. In this study we conducted a mixed-method sequential exploratory study with students co-enrolled in General Chemistry II and Introductory Biology I to better understand what students perceived to be the "take-home" messages of these courses (i.e., core ideas) and the connections between these courses. We found that students identified a range of ideas from both courses; further analysis of students' explanations and reasoning revealed that, when students talked about their chemistry ideas, they were more likely to talk about them as having predictive and explanatory power in comparison with reasons provided for their biology big ideas. Furthermore, students identified a number of overlapping ideas between their chemistry and biology courses, such as interactions, reactions, and structures, which have the potential to be used as a starting place to support students building a more coherent network of knowledge.

The purpose of this paper is to share the iterative process we used to design a task that elicits causal mechanistic reasoning and how the subsequent student responses can be analyzed. Our goal in this task is to strike a balance between eliciting as much student knowledge as possible without providing so much structure that the answer becomes obvious. The task development was approached using (1) a resources perspective of learning, (2) principles of scaffolding, and (3) evidence-centered design, for which we specified evidence that would be considered a fully causal mechanistic explanation. That is, an explanation which pays explicit attention to the properties, interactions, and behaviors of entities that are involved at a scalar level below the phenomenon under consideration. Since our eventual goal is to characterize how students use knowledge across disciplinary boundaries, the phenomenon of protein--ligand binding was chosen as the context for this task, because it requires students to apply ideas learned in chemistry courses to a biological phenomenon. After three rounds of iterative refinement, a final task was developed. To characterize students' responses to this task, we developed a coding scheme which can be used to code explanations based on the presence or absence of three key ideas relevant to this phenomenon. In this paper, we share the detailed processes and approaches used in task development, which we hope will provide insight into instructors and researchers as they, too, develop such tasks to explore student reasoning.

Calls for diversity, inclusion, and equity in chemistry and science education have been ongoing. However, some faculty may find it difficult to challenge systemic inequities due to their pervasiveness. We posit that one working area for addressing systemic inequities in chemistry and science education is the removal of grading on a curve from our practices. Though this practice may be seen as traditional and "what people have always done", we offer nine critiques of this approach and how it may exacerbate systemic inequities rather than help students. These critiques challenge a variety of taken for granted assumptions about grading on a curve, including that it is more objective, is more efficient, and assists in controlling for grade inflation. Through our critiques, we hope to highlight that these assumptions are not entirely accurate and/or they act more as a sorting mechanism than as a way to evaluate learning. Using a brief history of grading in the United States, including some that speak to the evolution of grading on a curve, empirical evidence, and expert perspectives on diversity, inclusion, equity, and persistence, the aim of this paper is to use our critiques of the assumptions of grading on a curve and challenge the taken for granted beliefs about the practice. Our goal is to offer a strong argument against grading on a curve so that it becomes a working area for faculty to address systemic inequities by removing the practice from courses and adopting more informative and equitable approaches to learning and assessment.

This study is a follow up to two earlier studies characterizing student real-time use of mechanistic arrows. In these previous studies, students were asked to predict a product by drawing a curved arrow mechanism using an interface that allowed recording and replay of student actions. In the present study two different student cohorts responded to the same tasks as the original studies: a cohort who were enrolled in a traditional organic course, and a cohort who were part of a transformed organic course (Organic Chemistry, Life, the Universe and Everything, OCLUE). Both cohorts improved in their ability to predict an appropriate product over the two semesters, and we found little meaningful difference in the ability of students from either cohort to predict the outcome of a familiar reaction. However, students in the OCLUE cohort were more likely to draw mechanistic arrows than the students from the traditional course. In contrast, when the task involved predicting the product of an unfamiliar reaction, OCLUE students were over three times more likely to draw mechanistically reasonable steps and produce a plausible product than students from the traditional cohort. We propose that the differences between the two cohorts emerge from the following: (1) explicit attempts in the OCLUE course to link drawing reactions mechanisms using the electron pushing formalism to the scientific practice of constructing explanations. It is our contention that this approach changes the arrow pushing mechanism from a skill to the construction of a model which students can use to predict and explain outcomes; and (2) the numerous opportunities in the OCLUE course to try out ideas without penalty, leading to a willingness to try to determine outcomes in unfamiliar situations.

What we emphasize and reward on assessments signals to students what matters to us. Accordingly, a great deal of scholarship in chemistry education has focused on defining the sorts of performances worth assessing. Here, we unpack observations we made while analyzing what "success" meant across three large-enrollment general chemistry environments. We observed that students enrolled in two of the three environments could succeed without ever connecting atomic/molecular behavior to how and why phenomena happen. These environments, we argue, were not really "chemistry classes" but rather opportunities for students to gain proficiency with a jumble of skills and factual recall. However, one of the three environments dedicated 14-57% of points on exams to items with the potential to engage students in using core ideas (e.g., energy, bonding interactions) to predict, explain, or model observable events. This course, we argue, is more aligned with the intellectual work of the chemical sciences than the other two. If our courses assess solely (or largely) decontextualized skills and factual recall we risk (1) gating access to STEM careers on the basis of facility with skills most students will never use outside the classroom and (2) never allowing students to experience the tremendous predictive and explanatory power of atomic/molecular models. We implore the community to reflect on whether "what counts" in the courses we teach aligns with the performances we actually value.

Computer-assisted analysis of students' written responses to questions is becoming a possibility due to developments in technology. This could make such constructed response questions more feasible for use in large classrooms where multiple choice assessments are often considered a more practical option. In this study, we use a previously developed prompt and coding scheme to characterize students' explanations of the origins of London dispersion forces in order to develop machine learning resources that can carry out such an analysis for large numbers of students. We found that by using large numbers of human coded student responses (N = 1,730) we could subsequently automatically characterize students' responses at a high level of accuracy compared to human coders. Furthermore, these resources were developed using responses from several different groups of students across multiple institutions to ensure both that our resources can work well with students from different backgrounds and that these computer resources can detect the different ways in which students explain this phenomenon. Such resources may help instructors to administer more complex open-ended assessment tasks to larger numbers of students and analyze the responses capturing language corresponding to causal mechanistic reasoning. Instructors could then use this information to better support their students' learning.

Three-dimensional learning is the name given to the vision for science education described in the National Academies consensus report "A Framework for K-12 Science Education." Of the three dimensions described in the Framework, the Disciplinary Core Ideas and the Science and Engineering Practices have been enthusiastically adopted by many in the science education community. However, the third dimension, Crosscutting Concepts (CCCs), has received less attention. Indeed, some researchers have begun to question both the necessity and the theoretical rationale for the CCCs. That being said, emerging work both supports the use of the CCCs and provides practitioners with approaches to their use that not only hold potential for supporting students' construction of deeper and more useful knowledge but also may provide an approach to learning that is more equitable. In this paper, examples highlight the use of CCCs as lenses, tools, bridges, or "rules of the game" (epistemic heuristics), that can support sensemaking about chemical phenomena in the context of three-dimensional learning.

The development of proficiency in the practices used by scientists and engineers is considered an important student outcome of laboratory instruction. We developed tasks to assess students' use and development of selected scientific and engineering practices in the general chemistry laboratory using an adapted evidence-centered design approach. In this paper, we provide a detailed description of the process of development and validation of these assessment tasks, using one of our tasks to illustrate the process. The tasks show strong evidence of validity and reliability for revealing students' understanding of scientific and engineering practices within the research context.

This three-year study builds on prior work analyzing students' causal mechanistic explanations about acid-base reactions. Here we extend that work to characterize and investigate how students construct causal mechanistic explanations of simple nucleophilic substitution reactions. After an initial pilot study, we adopted a modified version of the original task prompt which was used in two subsequent years to compare responses from students enrolled in a transformed organic chemistry course (Organic Chemistry, Life, the Universe and Everything) and a traditional organic chemistry course. Student responses were sampled in the middle of the first semester organic chemistry, just after they had learned the material, and once again at the end of the course, to identify how responses changed over time. Our findings from this study include (1) eliciting causal mechanistic explanations requires careful scaffolding to activate productive elements of a response, and (2) students from a transformed course are more likely to construct a causal mechanistic explanation at the end of Organic Chemistry 2 than students from the control group, suggesting that if students are to retain the use of valuable knowledge, this must be supported by instruction and course expectations.

Inquiry-style laboratory courses, in which students engage in open-ended projects rather than a prescribed set of experimental steps ("cookbooks"), are becoming increasingly popular at the undergraduate level. Reformed curricula require reforms in training teachers; in the case of large universities, laboratory instructors are typically graduate teaching assistants (TAs). The General Chemistry Laboratory courses at a large, public, research-intensive university in the Midwestern region of the United States recently underwent a transformation from a "cookbook" to a project-based lab, and despite efforts to improve training, TAs continue to express difficulty teaching the course. To determine the source of these difficulties, we conducted multiple video observations and semi-structured interviews with seven TAs throughout one semester. We report TAs' beliefs about what is expected of them, their philosophical alignment to perceived expectations, and a comparison of the Lab Coordinator's expectations to TAs' actual teaching practices. We found that the TAs generally agreed with behaviors they were expected to perform, but responses to actions they were not supposed to do indicated that they were unsure of what the Lab Coordinator expected and personally believed that an ideal TA would perform those actions. This work highlights a need to clearly communicate the aims and expectations in a course and the rationale for those choices.

Constructing and critiquing evidence-based claims is centrally important to aspiring medical professionals and to scientists more generally. Accordingly, The National Academy of Science's "Framework for K-12 Science Education" describes engaging in argument from evidence as one of the practices that characterize work in science. However, despite the central role argumentation plays in construction and refinement of evidence-based explanations and models, it is very often absent from K-16 science learning environments. Here, we frame argumentation from spectroscopic evidence in terms of flexible application of a series of procedures to pull information from spectroscopic traces and use this evidence to inform claims as to the structure of an unknown molecule. Through analysis of responses to several multipart assessment items, we examined how students analyzed, interpreted and used spectroscopic evidence to inform their claims. We found that students were fairly adept at analyzing and interpreting data from infrared and [superscript 13]C NMR traces as well as indicating correspondence between proton environments in their structural prediction and appropriate [superscript 1]H NMR peaks. Unfortunately, none of these tasks were significantly associated with student success in proposing a claim consistent with an entire corpus of spectroscopic data. Further, scaffolding of the task prompt had no impact on student ability to successfully construct evidence-based structural predictions. Our findings indicate that students will require significant support to use their procedural knowledge flexibly in order to iteratively construct and critique claims supported by spectroscopic evidence.

The fundamental structure of a typical mainstream two-semester organic chemistry course, populated mostly by life science majors and taught at universities throughout the United States, has changed little since the 1970s. However, much of the research on learning in organic chemistry has been devoted to characterizing student difficulties of various types, and there is now persuasive evidence that organic chemistry as currently taught is neither effective nor relevant for a majority of students. In an attempt to address the problems with traditional approaches to organic chemistry instruction, we have developed an approach to the design of a transformed organic chemistry course (Organic Chemistry, Life, the Universe and Everything or OCLUE) suitable for the vast majority of organic chemistry students that includes (1) using the Framework of three-dimensional learning (3DL) to support knowledge in use and (2) emphasizing biologically important mechanisms. In this course, topics are connected to core ideas by using scientific practices, such as constructing models and explanations, analyzing and interpreting data, and emphasizing causal mechanistic reasoning. Here we discuss the theory and the decisions that went into the development of the course, including the compromises made and the rationales behind those choices. The outcome is a course that emphasizes causal mechanistic reasoning, has an increased focus on biologically prevalent reactions, and uses spectroscopy early and often to support evidence-based arguments about structure-property relationships. The materials we have developed are freely available to students and to potential users.

London dispersion forces (LDFs) are the most fundamental of the noncovalent interactions in that they are interactions that act between all molecular species and require only that students can use the "electron cloud" model of atomic structure. In this longitudinal study we investigate how students respond to prompts, designed to elicit causal mechanistic reasoning about the origins of LDFs, using a modified coding scheme from a previous study. We find that including explicit scaffolding improves students' representations of the mechanism compared to student responses to an unscaffolded prompt. When, on a later administration of a similar prompt, the scaffolding is removed, the sophistication of the students' representations decreases, but does not decline to the level of students who had never been exposed to a scaffolded prompt. We also explore the connection between student drawing and writing and find that there is a significant association between the reasoning level of the drawing and the written explanation. Finally, we show that there appears to be no significant difference between performance on ungraded (formative) and graded (summative) items that are administered in the second semester when LDFs are not explicitly covered. That is, students respond to ungraded homework activities similarly to examinations at time points where LDFs are not explicitly discussed in the course.

Widespread adoption of the Next Generation Science Standards (NGSS) has created a need to carefully consider how chemistry curricula should support students in understanding the world in terms of atomic/molecular behavior. We argue that Standards-aligned coursework should be "core-ideas centered" due to evidence that curricula embedded in scaffolded progressions of core ideas can help students develop, organize, and use their knowledge to make molecular-level sense of phenomena. Our team of teachers and researchers has previously proposed a model for developing an integrated, core idea focused introductory chemistry curriculum by adapting the conceptual progressions underpinning the evidence-based undergraduate chemistry course Chemistry, Life, the Universe, and Everything (or CLUE). Here, we examine the efficacy this NGSS-aligned chemistry course (called High School CLUE or HS-CLUE) in helping students connect atomic/molecular structure to observable properties. This study made use of a cross-sectional approach to compare the responses of three student cohorts, each instructed according to a different curriculum, on a three-part structure--properties assessment. There is a positive association between enrollment in HS-CLUE and (1) viewing Lewis structures as models, (2) representing hydrogen bonds as "between" molecules, and (3) constructing scientifically accurate, molecular-level explanations for the difference in boiling point between two substances. These associations were primary drivers for the significant relationship between learning environment enrollment and student responses in the majority of instances examined. Our findings provide preliminary evidence that structuring high school chemistry instruction around validated progressions of core ideas supports students in relating atomic/molecular structure to properties.

Connecting the behavior of invisible (to the naked eye) particles governed by the principles of quantum mechanics to the world we can see and touch requires a host of inferences, almost none of which can be extrapolated from experience. Molecular-level sensemaking thus relies upon intellectual resources that must be developed in large part by formal learning environments. Over a decade of research at the college-level indicates that centering instruction around scaffolded progressions of core ideas can help students cultivate, organize, and use their disciplinary knowledge to explain and model a range of phenomena. Informed by this literature, we have adapted a core-idea centered, evidence-based undergraduate general chemistry curriculum for use in high school. Our adaptation process, which was a collaborative effort between researchers and classroom teachers, is described in detail with emphasis on alignment between the Next Generation Science Standards and our materials. Efforts reported here represent a first-in-class model for high school curriculum development wherein conceptual progressions developed and validated at the college level form the basis for high school coursework.

Over the past 20 years research on reform efforts aimed at the chemistry laboratory has focused on different aspects of students' experiences including increasing content knowledge, improving student attitudes toward chemistry, incorporating inquiry activities, and providing students a hands-on experience related to the chemistry concepts learned in lecture. While many of these efforts have been designed to incorporate inquiry activities, because this term is somewhat nebulous, it can be difficult to identify which aspects of the laboratory support inquiry. The Scientific and Engineering Practices outlined in the "Framework for K-12 Science Education" provide a new way to identify and characterize laboratory activities more precisely. This work compares two laboratory curricula in terms of the extent to which the curricula as a whole provide opportunities for students to engage in scientific practices and characterizes in which sections of a laboratory activity (prelab/procedure, data manipulation/analysis, conclusions/report out) students most frequently engage specific scientific practices. Further, this study demonstrates how a modified version of a published protocol for evaluating incorporation of science practices into assessment items (the 3-Dimensional Learning Assessment Protocol) can be used to evaluate laboratory activities in a systematic way. Ways in which such an analysis can inform and support the revision of laboratory curricula are also discussed.

The study presented here is a follow-up to a previous report in which we investigated how general-chemistry students in a transformed curriculum reason about simple acid-base reactions. In the present study, we use and adapt the previously developed coding scheme for a longitudinal study in which we follow students from general chemistry through organic chemistry. We find that (i) generally, the manner in which students reason about acid-base reactions increases in sophistication over the course of a two-semester sequence of organic chemistry; (ii) there is little difference in reasoning between students at the end of a transformed general-chemistry course and a similar cohort at the beginning of organic chemistry; (iii) the nature of a student's general-chemistry experience has a profound effect on the sophistication of their reasoning in that students from a transformed general-chemistry course are more likely to provide causal mechanistic explanations for simple acid-base reactions than students with other general-chemistry experiences; and (iv) the type of acid-base reaction that the students discuss impacts the type of reasoning they exhibit. We find that when asked to explain a Lewis acid-base reaction, students are less likely to invoke electrostatic ideas.

The relationship between chemical structure and physical and chemical properties is essential to chemistry. Studies have shown that students have difficulty using structural representations to predict properties, which is not surprising because of the sequence of inferences that are required for sense-making. However, obtaining a nuanced model of students' understanding depends on how information is elicited. This study investigated how the phrasing of the question prompt may elicit students' understanding of structure-property relationships. Students were given a two-part assessment: (1) four multiple-choice questions assessing students' self-reported abilities to predict structure-property relationships, and (2) three questions requiring students to predict, argue, and explain a boiling point trend. Two groups of students were selected to determine the sensitivity of the instrument (one with less explicit instruction of structure-property relationships and one with more explicit instruction). We found that Part I of the assessment was able to differentiate between these two groups of students. The group with more explicit instruction was further analyzed to determine how their prediction on a boiling point task connected to their arguments and explanations of the phenomenon. Even though 64% of students answered the boiling point ranking task correctly, the students typically provided less complete arguments as to why that structure had a higher boiling point. However, after scaffolding (i.e., providing relevant information for the phenomenon) and asking for an explanation, students' responses began to include a much more mechanistic understanding, suggesting that having students provide explanations instead of constructing an argument would display their reasoning at a deeper level.

While many university students take science courses in multiple disciplines, little is known about how they perceive common concepts from different disciplinary perspectives. Structure-property and structure-function relationships have long been considered important explanatory concepts in the disciplines of chemistry and biology, respectively. Fourteen university students concurrently enrolled in introductory chemistry and biology courses were interviewed to explore their perceptions regarding 1) the meaning of structure, properties, and function; 2) the presentation of these concepts in their courses; and 3) how these concepts might be related. Findings suggest that the concepts of structure and properties were interpreted similarly between chemistry and biology, but students more closely associated the discussion of structure-property relationships with their chemistry courses and structure-function with biology. Despite receiving little in the way of instructional support, nine students proposed a coherent conceptual relationship, indicating that structure determines properties, which determine function. Furthermore, students described ways in which they connected and benefited from their understanding. Though many students are prepared to make these connections, we would encourage instructors to engage in cross-disciplinary conversations to understand the shared goals and disciplinary distinctions regarding these important concepts in an effort to better support students unable to construct these connections for themselves.

Despite the number of university students who take courses in multiple science disciplines, little is known about how they connect concepts between disciplines. Energy is a concept that underlies all scientific phenomena and, as such, provides an appropriate context in which to investigate student connections and misconnections across disciplines. In this study, university students concurrently enrolled in introductory chemistry and biology were interviewed to explore their perceptions of the integration of energy both within and across the disciplines, and how they attempted to accommodate and reconcile different disciplinary approaches to energy, to inform future, interdisciplinary course reform. Findings suggest that, while students believed energy to be important to the scientific world and to the disciplines of biology and chemistry, the extent to which it was seen as central to success in their courses varied. Differences were also apparent in students' descriptions of the molecular-level mechanisms by which energy transfer occurs. These findings reveal a disconnect between how energy is understood and used in introductory science course work and uncovers opportunities to make stronger connections across the disciplines. We recommend that instructors engage in interdisciplinary conversations and consider the perspectives and goals of other disciplines when teaching introductory science courses.

As chemists, we understand that science is more than a set of disconnected facts. It is a way of investigating and understanding our natural world that involves things like asking questions, analyzing data, identifying patterns, constructing explanations, developing and using models, and applying core concepts to other situations. This paper uses the concept of three-dimensional (3D) learning, presented in "A Framework for K-12 Science Education", to reconceptualize and develop assessment items that require students to integrate chemistry core ideas with scientific practices and crosscutting concepts. Developing 3D assessments from scratch is time-consuming and beyond the scope of most faculty work. Here we present an alternate approach: We provide a detailed description of ways in which instructors can take current assessment questions and modify them to align with three-dimensional learning by focusing on the evidence that is sought about what students know and can do with their knowledge.

In recent years, much of the emphasis for transformation of introductory STEM courses has focused on "active learning", and while this approach has been shown to produce more equitable outcomes for students, the construct of "active learning" is somewhat ill-defined and is often used as a "catch-all" that can encompass a wide range of pedagogical techniques. Here we present an alternative approach for how to think about the transformation of STEM courses that focuses instead on what students should know and what they can do with that knowledge. This approach, known as three-dimensional learning (3DL), emerged from the National Academy's "A Framework for K-12 Science Education", which describes a vision for science education that centers the role of constructing productive causal accounts for phenomena. Over the past 10 years, we have collected data from introductory biology, chemistry, and physics courses to assess the impact of such a transformation on higher education courses. Here we report on an analysis of video data of class sessions that allows us to characterize these sessions as active, 3D, neither, or both 3D and active. We find that 3D classes are likely to also involve student engagement (i.e. be active), but the reverse is not necessarily true. That is, focusing on transformations involving 3DL also tends to increase student engagement, whereas focusing solely on student engagement might result in courses where students are engaged in activities that do not involve meaningful engagement with core ideas of the discipline. [ABSTRACT FROM AUTHOR]

Organic chemistry is often promoted as a course designed to cultivate skill in scientific "ways of thinking." Expert organic chemists perceive their field as one in which plausible answers to complex questions are arrived at through analytical thought processes. They draw analogy between problem solving in organic chemistry and diagnosis of a disease, which is of central importance to physicians-in-training. To determine whether or not assessments deployed in organic chemistry align with the rhetoric used to promote the course to premedical students, we characterized 118 organic chemistry assessment items given to students at elite universities. The overwhelming majority of the questions examined were not capable of eliciting evidence of student engagement in the scientific and engineering practices (the disaggregated components of inquiry) defined by the "Framework for K-12 Education." Dissonance between assessment focus and rhetoric used in course promotion is troubling as assessments convey a strong implicit message about the objective of a course. If exams focus chiefly on recall, application of simple algorithms, and pattern recognition, students will infer that memorization of content is the chief aim of organic chemistry. Herein, we examine how prompts might be modified or constructed to better engage students in one or more of the scientific and engineering practices in the context of organic chemistry. Both constructed response and selected response prompts are discussed.

In this paper we discuss how and why core ideas can serve as the framework upon which chemistry curricula and assessment items are developed. While there are a number of projects that have specified "big ideas" or "anchoring concepts", the ways that these ideas are subsequently developed may inadvertently lead to fragmentation of knowledge, rather than construction of a coherent, contextualized framework. We present four core ideas that emerged as a consequence of a transformation effort at our institution and discuss the relationships between core ideas and more recognizable topics in the context of a general chemistry course. We show how commonly taught topics can be supported and developed on the basis of the core ideas and discuss why this approach can lead to a more expert-like framework upon which students can build their future understanding.

One of the most mystifying products on the market for people at any age is the glow stick: a plastic tube that, when snapped, creates a flood of bright, brilliantly colored light without the use of electricity or significant production of heat. In this case, the chemiluminescence reaction also provides an exciting phenomenon through which we can engage students in the Scientific and Engineering Practices. This laboratory project has been developed both to pique students' interest about the task at hand and to have them practice science in a more authentic way than a traditional "cookbook" experiment. In completing this project, students will not only gain an understanding of the factors affecting the rate of the chemiluminescence reaction but also be able to create their own procedures, analyze and interpret their data, and construct an evidence-based argument from their results.

Many introductory biology courses amount to superficial surveys of disconnected topics. Often, foundational observations and the concepts derived from them and students' ability to use these ideas appropriately are overlooked, leading to unrealistic expectations and unrecognized learning obstacles. The result can be a focus on memorization at the expense of the development of a meaningful framework within which to consider biological phenomena. About a decade ago, we began a reconsideration of what an introductory course should present to students and the skills they need to master. The original Web-based course's design presaged many of the recommendations of the "Vision and Change" report; in particular, a focus on social evolutionary mechanisms, stochastic (evolutionary and molecular) processes, and core ideas (cellular continuity, evolutionary homology, molecular interactions, coupled chemical reactions, and molecular machines). Inspired by insights from the Chemistry, Life, the Universe & Everything general chemistry project, we transformed the original Web version into a (freely available) book with a more unified narrative flow and a set of formative assessments delivered through the beSocratic system. We outline how student responses to course materials are guiding future course modifications, in particular a more concerted effort at helping students to construct logical, empirically based arguments, explanations, and models.

Acid-base chemistry is central to a wide range of reactions. If students are able to understand how and why acid-base reactions occur, it should provide a basis for reasoning about a host of other reactions. Here, we report the development of a method to characterize student reasoning about acid-base reactions based on their description of "what" happens during the reaction, "how" it happens, and "why" it happens. We show that we can reliably place student responses into categories that reflect the model of acid-base reactivity used and whether the students invoke an electrostatic causal argument. However, the quality of student responses is highly dependent on the structure of the task prompt, which must be structured to provide students with enough information for them to understand what is needed. In general, students who construct responses that invoke a causal mechanistic Lewis model are more likely to draw appropriate curved arrow reaction mechanisms.

The ability to use a chemical structure to predict and explain phenomenon is essential to a robust understanding of chemistry; however, previous research has shown that students find it difficult to make the connection between structure and properties. In this study we examine how student recognition of the connections between structure and properties evolves during the first two years of college chemistry courses. In addition, we investigate how an alternative general chemistry curriculum (Chemistry, Life, the Universe and Everything (CLUE)) impacts students' understanding during these first two-years. Using discrete-time survival analysis to analyze student responses to the Implicit Information from Lewis Structures Instrument (IILSI), we found that it takes multiple semesters for students enrolled in a traditional curriculum to recognize that chemical structures can be used as models to predict chemical and physical properties. Students in the CLUE curriculum, however, tend to make this connection earlier than a matched cohort of students from a traditional curriculum, and this advantage is maintained throughout the two semesters of organic chemistry. In general, the control group takes an additional year of organic chemistry to reach the same level as the CLUE students after a year of general chemistry.

Intermolecular forces (IMFs), or more broadly, noncovalent interactions either within or between molecules, are central to an understanding of a wide range of chemical and biological phenomena. In this study, we present a multiyear, multi-institutional, longitudinal comparison of how students enrolled in traditional general chemistry courses and those in a transformed general chemistry course (Chemistry, Life, the Universe and Everything, or CLUE) represent intermolecular forces in the context of small molecules. For multiple cohorts of students at two different universities, we found that students who participate in the CLUE curriculum were significantly more likely than those in a traditional curriculum to indicate (correctly) that intermolecular forces occur between, rather than within small molecules. In a longitudinal study, we followed the students from one cohort through the subsequent year of organic chemistry and found that the differences between the CLUE and traditional students persisted over the course of two years of chemistry instruction. In general, students who are enrolled in the transformed general chemistry curriculum have a more scientifically correct and more coherent understanding of IMFs. The finding that a majority of students leave general chemistry without a coherent understanding of the difference between covalent and noncovalent interactions must certainly impact their subsequent understanding of chemical and biological phenomena.

Longitudinal studies can provide significant insights into how students develop competence in a topic or subject area over time. However, there are many barriers, such as retention of students in the study and the complexity of data analysis, that make these studies rare. Here, we present how a statistical framework, discrete-time survival analysis, can help overcome these barriers to longitudinal assessment studies using data from our research on students' understanding of structure-property relationships in chemistry. In the study presented, we administered the "Implicit Information from Lewis Structures Instrument" (IILSI)--an instrument designed to elicit from students what information can be predicted using a Lewis structure--to three cohorts of students at five time points over a two-year period, throughout their general chemistry and organic chemistry courses, to determine the ways in which student ideas about structure-property relationships evolved. Using survival analysis, we were able to identify both "whether" and "when" learning occurred over the two-year period. The single model also allowed us to construct trajectories to determine the ways in which students developed the ideas that underlie structure-property relationships in chemistry.

The ability to use representations of molecular structure to predict the macroscopic properties of a substance is central to the development of a robust understanding of chemistry. Intermolecular forces (IMFs) play an important role in this process because they provide a mechanism for how and why molecules interact. In this study, we investigate student thinking about IMFs (that is, hydrogen bonding, dipole-dipole interactions, and London dispersion forces) by asking general chemistry college students to both describe their understanding in writing and to draw representations of IMFs. Analysis of student drawings shows that most students in our study did not have a stable, coherent understanding of IMFs as interactions "between" molecules. At least 55% of the students in our study unambiguously represented each IMF an interaction or bond "within a single molecule," while only 10-30% of students represented each IMF as an interaction between molecules. Furthermore, the majority of students (59%) were not consistent in the way that they represented the different IMFs (as within or between). That is, their representations varied depending on the IMF. Student written descriptions of intermolecular forces were typically quite ambiguous, meaning that it was not possible to determine from the student description alone whether the student understood IMFs as bonds or interactions. It was only when the student's representation was consulted that we could determine whether a particular student had an appropriate understanding of IMFs. We believe that in situations where spatial information is crucial, free-form drawn representations are more likely to provide meaningful insight into student thinking.

There is a strong case to be made that the goal of science is to develop explanatory theories that help us organize our understanding and make predictions about the natural world. What then, is the goal of science education? What is it that we want students to know and be able to do, and how do we achieve these goals? Here, I argue that one overarching goal is to help students construct causal, mechanistic explanations of phenomena. In chemistry this means we are working to help students use their understanding of molecular level interactions to explain and predict macroscopic events. Furthermore, while constructing explanations is an important goal in itself, the very act of constructing explanations helps students develop a deeper understanding, and provides the kind of intellectual satisfaction that memorizing facts cannot. I hope to convince you that our current approaches to assessing student learning are, in fact, all too often counterproductive and almost certainly contribute to students' inability to connect ideas and develop a useful understanding of chemistry and that these assessments send the wrong message about what chemistry means (and why it is valuable). I will offer some suggestions how we might design more meaningful approaches to curriculum development and assessment of student understanding. After reading this essay, I hope that I will have convinced you that: (i) if we value something, we must assess it; (ii) we cannot assume students will construct a coherent framework from the fragments we teach; and (iii) we must design assessments that provide us with enough evidence to make an argument that the student understands.