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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.

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 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.

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.

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.

Die Forderung des Interesses und der Freude am Fach sowie der Erwerb eines grundlegenden Verstandnisses chemischer Konzepte sind wesentliche Ziele des Chemieunterrichts. Diese motivationalen und kognitiven Personenmerkmale pragen nicht nur das Handeln der Schulerinnen und Schuler im Unterricht, sondern auch auserhalb der Schule. In dieser Studie wurde daher untersucht, inwieweit sich die Freude am Chemieunterricht, das Konzeptwissen und das individuelle Interesse der Schulerinnen und Schuler an der Domane Chemie gegenseitig beeinflussen. Hierzu wurde in einer langsschnittlichen Fragebogenstudie das individuelle Interesse, die Freude und das Konzeptwissen von N = 756 Gymnasiasten (52 % weiblich, Alter zum Studienbeginn = 14,7 Jahre) in der neunten, zehnten und elften Jahrgangsstufe erfasst sowie die Entwicklung der einzelnen Konstrukte und Wechselwirkungen zwischen den Konstrukten, d. h. Effekte auf die individuelle Veranderung uber die Zeit, mittels latenter Strukturgleichungsmodelle untersucht. Univariate Analysen zeigen einen geringen Abfall des individuellen Interesses sowie einen moderaten Abfall der Freude und zeitgleich einen starken Anstieg des Konzeptwissens. Hinsichtlich des Zusammenhangs zwischen den Konstrukten deuten bivariate Latent Change Score Modelle auf beidseitige Wechselwirkungen zwischen den drei Konstrukten hin. Bei gleichzeitiger Berucksichtigung aller drei Konstrukte mittels trivariater Analysen zeigen sich weiterhin reziproke Zusammenhange zwischen der Freude und dem Konzeptwissen, jedoch nur einseitig positive Effekte der Freude und des Konzeptwissens auf die Veranderung des individuellen Interesses. Die Befunde unterstreichen die Relevanz motivationaler Variablen fur das Lernen und weisen auf Potentiale einer gezielteren Integration von Interessen der Schulerinnen und Schuler in den Chemieunterricht hin.

A central goal of chemistry education is to enable students to gain a broad understanding of central chemical concepts. To support students in achieving this goal, theoretically grounded and empirically validated models of developmental trajectories are needed to inform instruction and to guide assessment. However, it is an ongoing debate how these developmental trajectories need to be formulated and how evidence to support these trajectories can be established. In a longitudinal study covering students’ understanding of three chemical concepts in grades 5 to 8 and 9 to 12, respectively, we aim to investigate how different approaches to analyse students’ responses to test items lead to diverging conclusions regarding developmental patterns across grades. Overall, students’ test scores indicate substantial learning gains from grade to grade, with small to medium effect sizes. In addition, students’ progression across grades on average follows the hierarchy of ordered levels of conceptual understanding that were used for the development of the test items. However, a more fine-grained analysis focusing on individual trajectories calls the assumption of a level-by-level development of individual students into question.

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 s...

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 on the same time are found interesting and relevant for the students.

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.

Energy is considered both as a disciplinary core idea and as a concept cutting across science disciplines. Most previous approaches studied progressing energy understanding in specific disciplinary contexts, while disregarding the relation of understanding across them. Hence, this study provides a systematic analysis of cross-disciplinary energy learning. On the basis of a cross-sectional study with n = 742 students from grades 6, 8, and 10, we analyze students’ progression in understanding energy across biology, chemistry, and physics contexts. The study is guided by three hypothetical scenarios that describe how the connection between energy understanding in the three disciplinary contexts changes across grade levels. These scenarios are compared using confirmatory factor analysis (CFA). The results suggest that, from grade 6 to grade 10, energy understanding in the three disciplinary contexts is highly interrelated, thus indicating a parallel progression of energy understanding in the three disciplinary contexts. In our study, students from grade 6 onwards appeared to have few problems to apply one energy understanding across the three disciplinary contexts. These findings were unexpected, as previous research concluded that students likely face difficulties in connecting energy learning across disciplinary boundaries. Potential reasons for these results and the characteristics of the observed cross-disciplinary energy understanding are discussed in the light of earlier findings and implications for future research, and the teaching of energy as a core idea and a crosscutting concept are addressed.

Fachtexte stellen Lesende im Unterricht bekanntermasen vor grose Herausforderungen. Es wird regelmasig bemangelt, dass die Texte aufgrund ihrer Gestaltung nicht fur die Zielgruppe geeignet seien. Eine Moglichkeit, dem zu begegnen, ist die sprachliche Veranderung der Texte, hierfur gibt es aus der Textverstandnisforschung auch belegte Empfehlungen. In dem hier vorgestellten Projekt wurden solche Masnahmen zur Vereinfachung der Texte in den Fachern Physik und Chemie eingesetzt und in drei aufeinanderfolgenden experimentellen Studien in randomisierten Gruppenvergleichen in einem Pra-Post-Design untersucht. Es zeigt sich erwartungswidrig, dass die hier angewandten Masnahmen die Textverstandlichkeit nicht beeinflussen – die Lesenden lernen aus allen Variationen gleich viel. Dies ist einerseits ermutigend, weil offensichtlich bestimmte Eigenschaften der Fachtexte unproblematisch sind. Andererseits ergibt sich damit die Frage, wie sich das Textverstandnis stattdessen verbessern lasst.

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.

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 manu...

Die Bildungsstandards stellen eine normative Festlegung uber die am Ende der 10. Klasse zu erlangenden Kompetenzen im Fach Chemie dar. Gleichzeitig wird mit den Bildungsstandards der Anspruch erhoben, dass sie Fahigkeiten und Fertigkeiten beschreiben, die hilfreich fur weiteres Lernen sind. Voraussetzung fur die empirische Untersuchung des Zusammenhangs der in der Sekundarstufe I erworbenen allgemeinen Kompetenzen im Fach Chemie und den im Rahmen einer Berufsausbildung zu erwerbenden beruflichen Kompetenzen sind Modelle uber die Strukturen der entsprechenden Kompetenzen in beiden Bereichen. Wahrend es verschiedene empirisch untersuchte Modelle zur Beschreibung der allgemeinen Kompetenzen im Fach Chemie gibt, fehlen fur den Bereich der beruflichen Kompetenzen in der Domane Chemie sowohl theoretisch fundierte Kompetenzstrukturmodelle als auch empirische Erkenntnisse. In dem vorliegenden Beitrag soll der Zusammenhang zwischen allgemeiner Kompetenz im Fach Chemie und der beruflichen Kompetenz von Chemielaboranten genauer bestimmt werden, indem zunachst ein Strukturmodell zur Charakterisierung der Kompetenz von Chemielaboranten entwickelt wird. Auf Basis eines Abgleichs der Modelle, mit denen die Beschreibung der mit dem mittleren Bildungsabschluss zu erlangenden chemiebezogenen Kompetenzen einerseits und der beruflichen Kompetenzen von Chemielaboranten andererseits erfolgt, werden dann konkrete Annahmen uber deren Zusammenhang abgeleitet. Im Ausblick werden Perspektiven fur die Prufung des entwickelten Strukturmodells sowie zur Untersuchung der Zusammenhange zwischen allgemeinen und beruflichen Kompetenzen aufgezeigt.

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. © 2016 Wiley Periodicals, Inc. J Res Sci Teach 53:683–708, 2016

Chemistry requires and combines both observable and mental representations. Still we know that learners often struggle in combining these perspectives successfully, especially when experimental observations contradict the model-based explanations, e.g. in interpreting the chemical equilibrium as dynamic processes while observing a static system without any visible changes. Digital media offer potentials that might not have been accessible to this degree until now. However, we do not know enough with regard to the degree and effects these media tools have in supporting learning processes but perhaps also in hindering them. This article presents four approaches on how to potentially make use of digital media in learning processes based on theoretical considerations and empirical investigations. The projects will explore applications of media as visualization, learning and investigation tools in chemistry education, embracing techniques from virtual realities to eye-tracking. Special Issue: Chemistry Education

In den letzten Jahren sind in vielen Ländern Kompetenzmodelle entwickelt worden, welche als Referenzsysteme für die Festlegung und Überprüfung von Bildungsstandards dienen. In vielen Fällen bleibt es jedoch eine offene Frage, wie spezifische Kompetenzen valide und reliabel erfasst werden können. So existieren beispielsweise keine spezifischen Tests oder theoretischen Modelle, welche die Kompetenz im zentralen naturwissenschaftlichen Kompetenzbereich - Ordnen, Strukturieren, Modellieren (in der Folge nur noch kurz: OSM) - des Schweizerischen Kompetenzmodells für die Naturwissenschaften zuverlässig erheben oder beschreiben können. Als Beitrag zur Klärung entwickeln wir hier basierend auf theoretischen Überlegungen ein Modell hierarchischer Komplexität für den Kompetenzbereich OSM (MHC-OSM) im Inhaltsbereich Chemie. Das Modell umfasst fünf Kompetenzstufen, deren theoretische Fundierung im Detail beschrieben wird. Eine erste Einordnung des Modells durch einen Vergleich mit der aktuellen Version des Lehrplans 21 sowie mit den seit 2011 festgeschriebenen Grundkompetenzen für die Naturwissenschaften beziehungsweise der Bildungsstandards für den mittleren Schulabschluss in Deutschland zeigt eine gute Passung. Zum Schluss wird aufgezeigt, wie das Modell empirisch validiert werden könnte.

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.

Sprache ist konstitutiv fur wissenschaftliches Handeln. Vor diesem Hintergrund kann aus dem Konzept der Scientific Literacy die sprachliche Forderung von Lernenden als Bildungsziel auch fur den naturwissenschaftlichen Unterricht abgeleitet werden. Fachdidaktische Forschung konzentriert sich bisher allerdings auf einzelne, ausgewahlte Aspekte, sodass weder ein einheitlicher theoretischer Rahmen noch eine koharente empirische Befundlage zu erkennen ist. Im vorliegenden Beitrag wird versucht, einige zentrale Befunde aus Sprachdidaktik, Linguistik, Fachdidaktik und Kognitionspsychologie in einem Uberblick darzustellen und zugleich Lucken der empirischen Forschung aufzuzeigen. Basierend auf bestehenden empirischen Befunden und Modellen unterschiedlicher Forschungsdisziplinen wird fur die drei naturwissenschaftlichen Facher Physik, Chemie und Biologie ein ubergreifendes Modell vorgeschlagen, das sich zunachst auf die Interaktion zwischen verschiedenen Personenfahigkeiten (Vorwissen und sprachliche Fahigkeiten) und Textmerkmalen naturwissenschaftlicher Texte bezieht, da hier der Grosteil der empirischen Evidenz vorliegt. Der Beitrag fokussiert somit auf das Verstandnis expositorischer Texte.

Background: Context-based learning approaches are used to enhance students’ interest in, and knowledge about, science. According to different empirical stud- ies, students’ interest is improved by ...

A perspective is presented on how the representation mapping framework by Hahn and Chater (1998) may be used to characterize reasoning during problem solving in chemistry. To provide examples for testing the framework, an exploratory study was conducted with students and professors from three different courses in the middle of the undergraduate chemistry curriculum. Each participant's reasoning while solving exam problems was characterized by comparing the stored knowledge representation used as a resource and the new instance representation associated with the problem being solved. Doing so required consideration of two ways in which abstraction occurs: abstractness of representations, and abstracting while using representations. The representation mapping framework facilitates comparison of the representations and how they were used. This resulted in characterization of reasoning as memory-bank or rule-based (rules processes), or similarity-based or prototype (similarity processes). Rules processes were observed in all three courses. Similarity-based reasoning seldom occurred in students, but was common to all of the professors’ problem solving, though with higher abstractness than in students. Examples from the data illustrate how representation mapping can be used to examine abstraction in problem solving across different kinds of problems and in participants with different levels of expertise. Such utility could permit identifying barriers to abstraction capacity and may facilitate faculty assessment development.

Chemical representations play an important role in helping learners to understand chemical contents. Thus, dealing with chemical representations is a necessity for learning chemistry, but at the same time, it presents a great challenge to learners. Due to this great challenge, it is not surprising that numerous national and international studies have shown that students have remarkable difficulties. Since most of the studies regarding chemical representations have focused on investigating high-school students' knowledge so far, little is known about university students' and especially student teachers' knowledge. The latter group is additionally challenged by the necessity of learning how to transform their own knowledge in order to teach chemical representations to their prospective students. Given this as a starting point, a paper-and-pencil test with 19 items in both semi-open and closed format was developed to investigate the extent of student teachers' knowledge of chemical representations. The present paper describes the design, validation, and psychometric analysis of this test instrument – the so-called Chemical Representations Inventory (CRI). The CRI includes a variety of chemical representations and chemical contents on both high-school and university level. Both classical test theory and Rasch modelling were used for the analysis. In addition, a qualitative analysis was performed, and factors which possibly influence the item difficulty were identified. Even though the CRI was originally developed for a sample of student teachers, it can also be used to measure chemistry students' knowledge on a basic level.

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.

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 difficult...

Die chemische Formelsprache pragt den Kompetenzbereich Kommunikation in einer besonderen, fachspezifischen Weise. Sie stellt einen eigenen Lerngegenstand dar, reprasentiert aber auch chemische Prozesse und Fachkonzepte nach prazisen Regeln. Fur das Lernen und Kommunizieren in und uber Chemie ist sie folglich unverzichtbar. Zahlreiche Untersuchungen zeigen jedoch nach wie vor, dass Schulerinnen und Schuler grose Probleme in der Interpretation und Verwendung von Symbolen, Formeln und Reaktionsgleichungen haben. Dieser Beitrag knupft zunachst an bekannte Ergebnisse aus der Lehr-Lern-Forschung an. Er hinterfragt weiterhin das Verstandnis ublicher Darstellungen in Lehrbuchern. Aufbauend auf eine Querschnittsuntersuchung werden schlieslich Anregungen fur die Unterrichtspraxis gegeben, deren weitere Diskussion die Autoren mit diesem Beitrag anstosen mochten. The chemical language is an important link between content knowledge and communication skills in chemistry. It is a learning goal in its own, but additionally it represents chemical processes and concepts according to precise rules. However, numerous studies have revealed remarkable difficulties of students concerning the interpretation and use of chemical symbols, formulae, and reaction equations for many years. This article ties in with well-known results from educational research. Furthermore, the understanding of representations in textbooks is exemplarily examined. In connection with a cross-sectional study, suggestions for teaching practice are presented in order to initiate further discussions on the topic of chemical language.

Current reforms in the education policy of various countries are intended to produce a paradigm shift in the educational system towards an outcome orientation. After implementing educational standards as normative objectives, the development of test procedures that adequately reflect these targets and standards is a central problem. This paper constructs the theoretical framework for the assessment of students' content knowledge in chemistry. The resulting scheme and manual were used to develop model-based tasks in various content areas. Students' performances in paper and pencil tests taken in school grades 6 to 12 were analyzed. The quantitative data were used for a reliable classification of the tasks. The results shed light on the development of content knowledge in chemistry as well as on the various systematic factors that influence students' performance.