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Students are known to have various difficulties in dealing with organic reaction mechanisms. A systematic classification of these difficulties appears necessary to design appropriate support. This paper presents insights into whether and how Bloom's revised taxonomy can be used to classify student difficulties in dealing with organic reaction mechanisms. We conducted an interview study with 12 undergraduate chemistry students using problem-solving tasks on nucleophilic substitution and elimination reactions to provide examples to test the classification. In our attempt at systemization, student difficulties are perceived as unachieved learning objectives. The classification reveals that student difficulties pertain to different cognitive process and knowledge dimensions. Specific major difficulties occurred within each cell of Bloom's revised taxonomy and for individual students. Our analysis suggests that general support for dealing with reaction mechanisms might be less beneficial for some students and that more adapted support is needed. Our approach of using Bloom's revised taxonomy to classify student difficulties might also benefit other domains to better understand student difficulties and evaluate appropriate support.

The use of texts is an indispensable resource for students' learning, especially in science domains. While developing understanding of a specific topic usually is the main goal of reading expository texts, an important consideration is how to best measure whether this understanding has been reached. In this study, we aimed to analyze gains in students' reading comprehension based on reading three expository texts on chemistry and physics topics. By means of a pre-post design, we assessed the reading comprehension of 261 eighth grade students with regard to three levels of reading comprehension. Latent change scores were estimated to analyze changes in students' total test scores, while also calculating difference scores based on the single items. Results indicate that students' topic-related comprehension increases from pre- to posttest, while gains seem to be limited to word and sentence level questions. In line with other studies, these findings stress that students would benefit from explicit strategy instruction, at least when learning from reading is the goal of using science texts in classrooms.

Students' interest is considered an important learning outcome, but it is also a relevant predictor for student learning, and future vocational choices. According to numerous studies, however, students' interest in STEM fields usually declines during the course of secondary education. From the perspective of science education, it is therefore necessary to foster or at least maintain students' interest. Despite the variety of approaches that have already been examined in order to promote student interest, the problem of low-interested students remains. Prior findings indicate that specific person characteristics and the students' perception of the situation seem to be moderate the effectiveness of many approaches. The current intensive repeated measure intervention study addresses the investigation of a possible interest trigger (formative assessment) and also the process that influences the perception of this trigger. Based on a sample of 9th-grade chemistry students (N = 200), three different interventions of formative assessment were implemented in regular classrooms. Students' situational interest was assessed repeatedly in short time intervals. Based on multilevel analyses, not all interventions were perceived as equally interesting by the students. While students' individual interest influences the perception of all interventions positively, the impact of gender, chemistry grade, and enjoyment varies across the interventions.

Reading comprehension is an essential skill for learning in general and in science classes. Problems with reading comprehension might hinder students' participation in learning science. Text in science includes specific language features that distinguishes it from narrative text, so should reading instruction be part of teaching science? The direct and inferential mediation (DIME) model of reading comprehension subsumes factors that influence reading comprehension. It was tested separately regarding narrative text as well as expository text in English; however, both have not been tested by directly comparing them to each other. In this study, we investigated to what degree general reading comprehension of narrative text is directly comparable to topic-specific reading comprehension of science text. Hence, first the applicability of the DIME model of reading comprehension in another language (i.e. German) was tested. Second, a general reading comprehension model was directly compared to a topic-specific model for reading comprehension of science text. Participants across the two studies were 704 German Grade 8 students who completed measures of comprehension and the DIME predictor variables. Results of two path analyses indicate the general applicability of the model for another language and additionally for both genres. However, some differences are highlighted that may be of importance in future science-specific studies as well as for teaching science.

Conceptual knowledge is a crucial tool for students to understand scientific phenomena. Knowledge about the structure and function of mental concepts potentially helps science educators to foster the acquisition of this tool. Specifically, the coherence of students' mental concepts is an intensely discussed issue within the related conceptual change discourse. While former discussions focused on the question of whether these conceptions are coherent or not, recent approaches describe them as dynamic systems behaving more or less coherently in different situations. In this contribution, we captured this dynamic behavior of individual concepts by means of network analysis. Transcribed video data of 16 pairs of students working on four subsequent experiments on energy were transformed into weighted networks, which in turn were characterized by standardized coherence parameters. These coherence parameters and more basic network parameters were correlated with students' pre-post scores of a multiple-choice test on the energy concept. We found that the coherence parameter is significantly related to the students' test scores. Even more intense relations are indicated if networks are calculated solely based on conceptual key terms. Implications as well as methodological constraints of this approach are discussed.

Background: To make students more interested and engaged in science, new teaching approaches have been developed aiming at higher order thinking. Context-based learning approaches emanate from an idea that science content knowledge should be presented in a relevant context for students to improve their learning outcomes as well as making them more engaged in science. Previous research on context-based learning approaches has shown positive results; however, researchers and teachers need to explicitly consider which aspects of the contextual settings young students perceive as interesting and relevant to improve chemistry education. Purpose: In this paper, the constructs of 'interest' and 'relevance' are explored to analyse which aspects of open-ended chemistry problems engage students. Sample and Design: Both qualitative interview data and quantitative survey data are elaborated on in three subsequent studies with Swedish upper secondary chemistry students. Students' statements when discussing contextualisation of chemistry problems are analysed in relation to analytical frameworks to explore students' perceived interest and relevance. Results: The results highlight the importance of connections to personal dimensions in chemistry to make students more engaged and interested in chemistry. The language of the context-based problems is also found essential as the students indicate trigger-words in the tasks influencing perceived interest and relevance. This in combination with students' distinction between high interest as a positive feeling, and high relevance as something important or worthwhile, are important results from this study. Conclusion: From the results, conclusions are drawn to help researchers and teachers develop chemistry problems aiming for higher order thinking, but at the same time are found interesting and relevant for the students.

Research in Organic Chemistry education has revealed students' challenges in mechanistic reasoning. When solving mechanistic tasks, students tend to focus on explicit surface features, apply fragmented conceptual knowledge, rely on rote-memorization and, hence, often struggle to build well-grounded causal explanations. When taking a resource perspective as a lens, students' difficulties may arise from either an unproductive or a missing activation of cognitive resources. Instructors' explanations and their guidance in teaching situations could serve as a lynchpin to activate these resources. Compared to students' challenges in building mechanistic explanations in Organic Chemistry, little is known about instructors' explanations when solving mechanistic tasks and how they shape their targeted explanations for students in terms of the construction and embedding of cause-effect rationales. This qualitative study aims to contribute to the growing research on mechanistic reasoning by exploring instructors' explanatory approaches. Therefore, we made use of the framing construct, intended to trigger certain frames with explicit instruction. Ten Organic Chemistry instructors (university professors and lecturers) were asked to solve case comparison tasks while being prompted in two scenarios: an expert frame and a teaching frame. Our analysis shows that there is a shift from instructors' mechanistic explanations in the expert frame towards more elaborated explanations in the teaching frame. In the teaching frame, contrary to what might be expected, complete cause-effect relationships were not always established and instructors differed in how they shaped their explanations. Additional explanatory elements were identified in both frames and their shift in use is discussed. Comparing approaches between frames sheds light on how instructors communicate mechanistic explanations and allows us to derive implications for teaching Organic Chemistry.

In this eye-tracking experiment, we compared instructional videos with static signals, dynamic signals and no signaling in a within-subject design. We tracked eye movements from 28 undergraduate chemistry students while they were watching instructional videos about reaction mechanisms in the different signaling conditions. Further, we assessed students' cognitive load, as well as retention performance. We employed a Latin square design to control for sequencing and content effects of the instructional videos. Our data showed that dynamic signals helped students to better focus their attention to the relevant features of the representations virtually across the entire time of the video presentation. Furthermore, dynamic signals increased retention performance while they decreased extraneous cognitive load. Overall, our findings show the crucial role of pairing the signaling principle with the temporal contiguity principle in instructional videos to help students navigate through complex symbolic representations and improve their learning success.

Research in science education agrees that one of the key challenges of learners in the discipline is certainly connecting domain-specific representations to the underlying concepts. One way of supporting students to make applicable connections is using purposefully designed highlighting techniques in multimedia instructions. In order to examine the influence of different highlighting techniques on learning, 171 chemistry undergraduate students were provided with tutorial videos either with static, dynamic or without highlighting. The results show that students viewing tutorial videos with dynamic highlighting gave more sophisticated answers in direct retention tasks. Furthermore, results indicate that low prior knowledge is compensated by both static and dynamic highlighting techniques. This finding is supported by causal mediation analysis, which indicates that the effect of prior knowledge is moderated by the different highlighting techniques. Besides student learning outcomes, students' evaluation of the different tutorial videos shows significant benefits of the highlighted instructions in terms of perceiving higher comprehensibility. The results support the use of appropriate highlighting techniques in instructional formats to foster a stronger link between conceptual knowledge and representations.

Reaction mechanisms commonly used in organic chemistry are a great challenge for students in terms of understanding the representation and inferring the appropriate chemical concepts. In order to support the process of identifying and selecting chemical concepts, purposefully designed case comparisons are widely used. While these tasks place great demands on students' problem-solving capabilities, it is unknown how learners distribute their attention on the complex and information-rich representations. Understanding students' visual decoding behavior when dealing with case comparisons could provide valuable insights into supporting students' problem-solving process. In this exploratory study, we employed eye-tracking methodology to observe beginner and advanced undergraduate chemistry students when working through case-comparison tasks. By establishing a novel eye-tracking measure, the fixation/transition ratio, distinct viewing behaviors could be observed. Results indicate significant differences between both status groups. Advanced students are overall faster in their decision-making and transition more frequently between the representations, indicating a higher selectivity for chemically relevant entities. Further, the results show a significant impact of the visual complexity of a representation on students' visual behavior. Implications for designing case comparisons and supporting students' decoding process are discussed.

The development of students' interest in school science activities, their understanding of central chemical concepts, and the interplay between both constructs across Grades 5-11 were analyzed in a cross-sectional paper-and-pencil study (N = 2,510, mean age 11-17 years). Previous empirical findings indicate that students' knowledge increases over the time of secondary school while students' interest, especially in natural science subjects, tends to decrease. Concomitantly, there is evidence for an increase in the positive coupling between interest and knowledge across time. However, previous studies mainly rely on rather global measures, for example, school grades or general subject-related interest, and focus on science as an integrated subject instead of specific disciplines, for example, chemistry. For this article, more proximal and differentiated measures for students' understanding of three chemical concepts (Chemical Reaction, Energy, Matter) and interest in seven dimensions of school science activities according to the RIASEC + N model (Realistic, Investigative, Artistic, Social, Enterprising, Conventional, and Networking; cf. Dierks, Höffler, & Parchmann, 2014) were applied. The results are in line with previous research indicating a general increase in conceptual understanding and a decline in students' interest for all school science activities. However, the interplay between conceptual understanding and interest differs across the seven dimensions. Interest in activities which are likely to promote cognitive activation (investigative, networking) or involving the communication of knowledge (social, enterprising, and networking) are increasingly connected to conceptual understanding, especially in upper secondary grades. Interest in guided hands-on activities (realistic) which are typical in secondary science teaching, however, shows only small positive correlations to students' conceptual understanding across all grades. Hence, in upper-secondary school, investigative, social, enterprising, and networking activities seem to provide opportunities to benefit most from the interrelation between students' interests and their understanding.

This paper presents the findings of a three-year longitudinal study (Grades 9-11; N = 756 students in German secondary schools; mean starting age = 14.7 years) that explores the development of and the interplay between upper-secondary students' individual interest and conceptual understanding in chemistry. Students' individual interest was assessed in seven dimensions of school science activities (realistic, investigative, artistic, social, conventional, and networking) according to Dierks et al.'s RIASEC+N model. The data was collected annually using paper-and-pencil questionnaires. In order to analyse the longitudinal relation between students' academic interest and conceptual understanding, Eccles et al.'s Expectancy-Value Theoretical Model of Achievement Choices (EEVT) was utilised and seven bivariate cross-lagged models were performed to investigate the assumed reciprocal relations between both constructs. Regarding the developmental progression of individual interest and conceptual knowledge, latent growth curve models indicate a small decrease in all of the seven dimensions of students' interest in school science activities and concomitant a moderate growth of students' conceptual understanding. Moreover, structural equation modelling suggests weak reciprocal relations between students' conceptual understanding and their interest in investigative, social and networking school science activities, respectively. Furthermore, students' interest in enterprising activities predicted their subsequent conceptual understanding. No systematic pattern of cross-lagged effects between the three remaining interest dimensions and conceptual understanding were found. The results indicate that school science activities, which provide the potential for cognitively activating learning opportunities, could enhance the relation between students' interest and conceptual understanding. Implications for teaching practice and further research are discussed.

Context-based learning has become a widespread approach in science education. While positive motivational effects of such approaches have been well established empirically, clear results regarding cognitive aspects of students' learning are still missing. In this article, we argue that this circumstance might be mainly rooted in the definition of context itself. Based on this argument, we shift from the issue of "if" contexts are cognitively beneficial to focus on the question of "which composition of contexts" is, at least by tendency, more effective than another. Based on theories of conceptual change, we therefore conducted a small-scale intervention study comparing two groups of students learning in different sets of contexts focusing on the same scientific concept--the cross-cutting concept of energy. Results suggest that learning in a more heterogeneous set of contexts eases transfer to new contexts in comparison to learning in a more homogeneous set of contexts. However, a more abstract understanding of the energy concept does not seem to be fostered by either of these approaches. Theoretical as well as practical implications of these finding are discussed.

Context-based learning aims to make learning more meaningful by raising meaningful problems. However, these types of problems often require reflection and thinking processes that are more complex and thus more difficult for students, putting high demands on students' problem-solving capabilities. In this paper, students' approaches when solving context-based chemistry problems and effects of systematic scaffolds are analysed based on the Model of Hierarchical Complexity. Most answers were initially assigned to the lowest level of the model; higher levels were reached without scaffolds only by few students and by most students with scaffolds. The results are discussed with regard to practical implications in terms of how teachers could make use of context-based tasks and aligned scaffolds to help students in this activity.

Science standards of different countries introduced disciplinary core ideas and crosscutting concepts--such as energy--to help students develop a more interconnected science understanding. As previous research has mostly addressed energy learning in specific disciplinary contexts, this study targets students' cross-disciplinary understanding of energy. Since no respective test instrument was available, we present the development and validation of an instrument that can be used to compare students' progressing energy understanding across contexts from biology, chemistry, and physics. In a cross-sectional study, we administered the new instrument to N = 752 students at the end of grades 6, 8, and 10. In addition to a detailed discussion of the instrument's reliability and validity, the study findings compare progressing energy understanding in the three disciplinary contexts. With regard to energy as a crosscutting concept, the results are then used to discuss how students' energy understanding may be connected across disciplinary boundaries.

Chemical representations serve as a communication tool not only in exchanges between scientists but also in chemistry lessons. The goals of the present study were to measure the extent of student teachers' knowledge about chemical representations, focusing on chemical formulae and structures in particular, and to explore which factors related to the education in school and university contribute to inter-individual differences. Using a quantitative cross-sectional design, 322 students from 12 German universities in different stages of their university education were tested with the Chemical Representations Inventory (CRI, Taskin, Bernholt, & Parchmann, 2015). In addition, a short questionnaire was administered containing demographic data and possible factors that could have an effect on students' success in solving the items of the inventory. The data was analyzed by using Rasch modeling. The results show that student teachers' knowledge about chemical representations is quite low, with an average of students' total achievement of 50% in the corresponding inventory on chemical representations. A multivariate linear model revealed that passing exam(s) in organic chemistry at university, the grade of school leaving certificate, gender as well as studying chemistry in upper secondary school on basic and advanced levels are significant predictors of student teachers' knowledge. In total, these predictors are able to explain 30.3% of the variance in the test results. The dominance of school-related variables in the regression analysis indicates that school education seems to be still important after several years of studying and is not equalized by education at university.

This study presents our attempt to elicit students' progression in understanding the matter concept. Past work has identified the big ideas about matter students need to understand, the many everyday understandings students hold about these ideas, and levels of understanding through which students progress in developing understanding of the big ideas, or the matter concept as a whole. None of this research, however, has investigated whether the hypothesized big ideas represent distinct ideas and if so, how students' progression in developing understanding of the big ideas compares across them. With our study, we aim to provide a more comprehensive picture about students' progression in understanding matter by investigating students' progression in developing understanding of four big ideas about matter (structure and composition, physical properties and change, chemical reaction, and conservation). Based on a framework developed from a systematic review of the literature that identifies five levels of understanding for each of the four big ideas, an instrument based on Ordered-Multiple-Choice (OMC) items was developed to assess students' level of understanding about each idea. This instrument was administered to N = 1,388 students from grades 6 to 13. Multi-dimensional Rasch analysis was used to analyze the data collected. Our analyses confirm that the four big ideas represent distinct ideas although our examination of students' progression in understanding these ideas suggests that three of them develop in parallel. A detailed comparison of students' progression suggests that the hypothesized levels mark a hierarchical series of levels through which all students progress in the same order although not necessarily at the same pace. Together with the instrument developed which provides an efficient and reliable way to assess students' understanding our work may help to inform future efforts in optimizing instruction about matter and investigating students' trajectories in developing an understanding of the matter concept.

Despite the importance of scientific inquiry in science education, researchers and educators disagree considerably regarding what features define this instructional approach. While a large body of literature addresses theoretical considerations, numerous empirical studies investigate scientific inquiry on quite different levels of detail and also on different theoretical grounds. Here, only little systematic research has analysed the different conceptualisations and usages of the overarching construct of scientific inquiry in detail. To close this gap, a review of the research literature on scientific inquiry was conducted based on a widespread approach to defining scientific inquiry as activities that students engage in. The main goal is to provide a systematic overview about the range and spectrum of definitions and operationalisations used with regard to single activities of the inquiry process in empirical studies. The findings from the review first and foremost illustrate the variability in the ways these activities have been operationalised and implemented. For each activity, studies differ significantly not only with respect to the focus, explicitness and comprehensiveness of their operationalisations but also with regard to the consistency of their implementation in the form of instructional or interventional components in the study and/or in the focus of the assessment of student performance. This has significant implications regarding the validity and comparability of results obtained in different studies, e.g. in the context of discussions concerning the effectiveness of inquiry-based instruction. In addition, the interrelation between scientific inquiry, scientific knowledge and the nature of science seems to be underexplored. The conclusions make the case for further theoretical work as well as empirical research.

Background: Complexity models have provided a suitable framework in various domains to assess students' educational achievement. Complexity is often used as the analytical focus when regarding learning outcomes, i.e. when analyzing written tests or problem-centered interviews. Numerous studies reveal negative correlations between the complexity of a task and the probability of a student solving it. Purpose: Thus far, few detailed investigations explore the importance of complexity in actual classroom lessons. Moreover, the few efforts made so far revealed inconsistencies. Hence, the present study sheds light on the influence the complexity of students' and teachers' class contributions have on students' learning outcomes. Sample: Videos of 10 German 8th grade physics courses covering three consecutive lessons on two topics each (electricity, mechanics) have been analyzed. The sample includes 10 teachers and 290 students. Design and methods: Students' and teachers' verbal contributions were coded manual-based according to the level of complexity. Additionally, pre-post testing of knowledge in electricity and mechanics was applied to assess the students' learning gain. ANOVA analysis was used to characterize the influence of the complexity on the learning gain. Results: Results indicate that the mean level of complexity in classroom contributions explains a large portion of variance in posttest results on class level. Despite this overarching trend, taking classroom activities into account as well reveals even more fine-grained patterns, leading to more specific relations between the complexity in the classroom and students' achievement. Conclusions: In conclusion, we argue for more reflected teaching approaches intended to gradually increase class complexity to foster students' level of competency.

Background: Context-based learning approaches are used to enhance students' interest in, and knowledge about, science. According to different empirical studies, students' interest is improved by applying these more non-conventional approaches, while effects on learning outcomes are less coherent. Hence, further insights are needed into the structure of context-based problems in comparison to traditional problems, and into students' problem-solving strategies. Therefore, a suitable framework is necessary, both for the analysis of tasks and strategies. Purpose: The aim of this paper is to explore traditional and context-based tasks as well as students' responses to exemplary tasks to identify a suitable framework for future design and analyses of context-based problems. The paper discusses different established frameworks and applies the Higher-Order Cognitive Skills/Lower-Order Cognitive Skills (HOCS/LOCS) taxonomy and the Model of Hierarchical Complexity in Chemistry (MHC-C) to analyse traditional tasks and students' responses. Sample: Upper secondary students (n = 236) at the Natural Science Programme, i.e. possible future scientists, are investigated to explore learning outcomes when they solve chemistry tasks, both more conventional as well as context-based chemistry problems. Design and methods: A typical chemistry examination test has been analysed, first the test items in themselves (n = 36), and thereafter 236 students' responses to one representative context-based problem. Content analysis using HOCS/ LOCS and MHC-C frameworks has been applied to analyse both quantitative and qualitative data, allowing us to describe different problem-solving strategies. Results: The empirical results show that both frameworks are suitable to identify students' strategies, mainly focusing on recall of memorized facts when solving chemistry test items. Almost all test items were also assessing lower order thinking. The combination of frameworks with the chemistry syllabus has been found successful to analyse both the test items as well as students' responses in a systematic way. The framework can therefore be applied in the design of new tasks, the analysis and assessment of students' responses, and as a tool for teachers to scaffold students in their problem-solving process. Conclusions: This paper gives implications for practice and for future research to both develop new context-based problems in a structured way, as well as providing analytical tools for investigating students' higher order thinking in their responses to these tasks.

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The fluent use of the chemical language is a major tool for successfully passing chemistry courses at school or university as well as for working as a chemist, since chemical formulae are both a descriptive and a heuristic tool. However, numerous studies have revealed remarkable difficulties of students with chemical formulae both at school and at university. Although analysed for decades, current studies and practical experiences indicate that the misinterpretation of symbolic representations by students is still an ongoing problem. This review intends not only to summarize but also to categorize students' problems and difficulties when dealing with chemical formulae as reported in empirical studies. For this purpose, two categories of descriptive character were deduced from the empirical data: the type of chemical formulae and the operational activities that were required in the tasks of the studies. All in all, 38 articles were analysed on the basis of these categories. Students' problems and difficulties are then reflected based on three main problem areas: language-based problems, problems due to conceptual understanding, and problems due to inadequate selection and interpretation of formulae. These three areas call for a broader perspective in the interpretation of students' problems and thus lead to a discussion of implications for further research and changes in teaching practice.

Helping students develop a sound understanding of scientific concepts can be a major challenge. Lately, learning progressions have received increasing attention as a means to support students in developing understanding of core scientific concepts. At the center of a learning progression is a sequence of developmental levels reflecting an idealized progression toward understanding a particular core concept. This sequence is supposed to serve as a basis for designing instruction that can foster learning as well as assessments that can monitor students' progression. So-called ordered multiple-choice (OMC) items have recently been suggested as a simple and effective way of assessing students' level of understanding of a core concept. This article details our efforts in developing an instrument for assessing students' understanding of the structure and composition of matter based on OMC items. Ten OMC items were developed and administered to a sample of N = 294 students in grades 6-12. Rasch analysis was used to investigate instrument functioning and to determine linear measures of person abilities and item difficulties. In addition to the OMC items, students were administered corresponding open-ended items in order to investigate the validity of the results obtained through the OMC items. Our findings suggest assessing students' understanding of scientific concepts through OMC items is indeed quite worthwhile and should be subject to further research.