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This study investigated the influence of practical problem-solving tasks (PPST) in promoting meaningful learning (ML) and retention in a nonlaboratory chemistry component of a physical science course for pre-service teachers (PSTs). It utilized a mixed-methods research using a modified quasi-experimental design followed by a detailed analysis of change in the conceptual understanding of case participants. The researcher employed mechanical and statistical matching to select 80 participants in two intact groups. The study's findings revealed that using PPST as a mode of instruction significantly promoted ML and meaningful retention of chemistry concepts. The study generated patterns of explanation, patterns of change in the level of conceptual understanding, and patterns of regression in understanding. The study further argued that PSTs exposed to PPST experienced ML as evidenced by (1) the outcome-significant differences in performances in ML and meaningful retention tests, (2) the process-qualitative evidence of positive change in conceptual understanding, and (3) the context-use of PPST designed for PSTs to engage in a learning process meaningfully. This study called for further research on the inclusion of PPST in other nonlaboratory classes in chemistry and other science subjects, both at secondary and tertiary level.

Teaching is a complex activity that demands paying attention to diverse components and relationships that affect the learning process, and acting with intentionality to build and nurture those connections. In this qualitative research study, we proposed and used an intentional-relational framework to explore differences in the relationships that four general chemistry instructors sought and acted to build with intention in their classes. Our goal was not to evaluate the quality of instruction but rather to characterize instructors' practices to gain insight into educational relationships that may affect student performance. All instructors in our sample manifested a strong interest in helping students succeed in their studies and relied on a variety of resources designed and integrated into their courses to support student learning. They mostly differed in the extent to which they attended and responded to contextual issues, intentionally seeking to make content relevant to students, helping them build connections between their interests and the discipline, and adapting resources to create more inclusive learning environments. These differences seem to affect student performance in common exams. Our study highlights the importance of analyzing the relationships that instructors build with intention to support professional development and teacher reflection, and better understand the impact of instructors' decisions on student performance.

A variety of research studies reveal the advantages of actively engaging students in the learning process through collaborative work in the classroom. However, the complex nature of the learning environment in large college general chemistry courses makes it challenging to identify the different factors that affect students' cognitive and social engagement while working on in-class tasks. To provide insights into this area, we took a closer look at students' conversations during in-class activities to characterize typical discourse patterns and expressed chemical thinking in representative student groups in samples collected in five different learning environments across four universities. For this purpose, we adapted and applied a 'Community of Learners' (CoL) theoretical perspective to characterize group activity through the analysis of student discourse. Within a CoL perspective, the extent to which a group functions as a community of learners is analyzed along five dimensions including Community of Discourse (CoD), Legitimization of Differences (LoD), Building on Ideas (BoI), Reflective Learning (RL), and Community of Practice (CoP). Our findings make explicit the complexity of analyzing student engagement in large active learning environments where a multitude of variables can affect group work. These include, among others, group size and composition, the cognitive level of the tasks, the types of cognitive processes used to complete tasks, and the motivation and willingness of students to substantively engage in disciplinary reasoning. Our results point to important considerations in the design and implementation of active learning environments that engage more students with chemical ideas at higher levels of reasoning.

In physics and chemistry, the development of problem-solving skills is necessary to become an expert. A simple cognitive model to analyse such development is proposed and tested. An exploratory research was conducted with expert professors and students in initial and advanced years. A think aloud procedure was used to obtain relevant data while the participants tried to solve undefined, open problems. Solving these problems required a particular skill representative of expertise: modelling reality using science. More than 1350 solving actions were collected and related to the mental representations elaborated, developed and inter-related by solvers. The proposed model was able to account for expert-novice differences in terms of the respective distributions of solving actions among the mental representations. Large differences appeared in the mental representation of Conceptual scientific Model. In addition, advanced and initial students showed similar and significant averages of unproductive actions, while experts took very few. Experts showed high convergence in their distributions of actions among the mental representations. If the outcomes were replicated with higher external validity, the model could help researchers to analyse the cognitive mechanisms in problem-solving, and teachers to better focus their efforts on specific students' lacks.

Several studies have highlighted the positive effects that active learning may have on student engagement and performance. However, the influence of active learning strategies is mediated by several factors, including the nature of the learning environment and the cognitive level of in-class tasks. These factors can affect different dimensions of student engagement such as the nature of social processing in student groups, how knowledge is used and elaborated upon by students during in-class tasks, and the amount of student participation in group activities. In this study involving four universities in the US, we explored the association between these different dimensions of student engagement and the cognitive level of assigned tasks in five distinct general chemistry learning environments where students were engaged in group activities in diverse ways. Our analysis revealed a significant association between task level and student engagement. Retrieval tasks often led to a significantly higher number of instances of no interaction between students and individualistic work, and a lower number of knowledge construction and collaborative episodes with full student participation. Analysis tasks, on the other hand, were significantly linked to more instances of knowledge construction and collaboration with full group participation. Tasks at the comprehension level were distinctive in their association with more instances of knowledge application and multiple types of social processing. The results of our study suggest that other factors such as the nature of the curriculum, task timing, and class setting may also affect student engagement during group work.

The unplanned shift to online instruction due to the COVID-19 pandemic challenged many instructors teaching large-enrollment courses to design learning environments that actively engaged all students. We looked at how one instructor used her instructional team--a group of student assistants with diverse, structured responsibilities--to adapt her large-enrollment (>500 students) introductory chemistry course to a live-remote format, as well as the impact the team's involvement had on students' reported experiences of online learning. We found that the instructional team's involvement was instrumental in adapting the course to the live-remote online format. The integration of the instructional team had a significant positive impact on students' experiences in the course, including their perceptions of social and cognitive engagement and teacher presence. Students in the section with the integrated instructional team also outperformed students in other sections of the same course on standardized course exams and final course grade. These results suggest that a structured instructional team composed of students can be a mechanism for promoting positive student experiences and learning in large-enrollment, remote STEM courses.

Various strategies have been promoted to increase student engagement in collaborative activities in chemistry courses, including the use of small portable whiteboards where students can represent and share ideas. In this paper, we summarize the results of a study designed to investigate how the use of small portable whiteboards during groupwork affects student engagement. In particular, we paid attention to how the use of whiteboards affected social processing, knowledge dynamics, and student contributions during in-class tasks in a college general chemistry class. Our findings reveal significant differences in student engagement during activities in which whiteboards are used compared to those in which these tools are not used. Although the use of whiteboards correlated with more instances of knowledge construction, overall effects are mixed, as the use of whiteboards more frequently led groups to split in pairs in the observed class. Our results suggest that the use of whiteboards should be carefully planned and managed by instructors to maximize benefits and reduce potential hindrances to collaborative work.

Improvement in student performance from educational reforms has driven current calls for changes in curricular, instructional, and assessment practices in higher education. Less research has addressed the possibility of such reforms aiding in resolving the well-documented inequities in educational outcomes between sexes and races/ethnicities in STEM courses. In this study, we compared a traditional and a reformed general chemistry course offered at a large public research-intensive university. Using hierarchical linear and logistical modeling, we assessed and investigated the inequities between sexes and races/ethnicities in the outcomes for these courses. Initial analysis looking at aggregated data (not by sex or ethnicity) showed the benefit of reforms specifically for students that had not been as academically well prepared as others. Novel findings for off-sequence (first semester taken in Spring) classes for both the traditional and reformed courses found a female-lead in course grades and benefits for Native Hawaiian or Pacific Islander, American Indian or Alaska Native, Latinx or Hispanic, and African American or Black (NALA) students. The on-sequence traditional course was found to have a male-lead in achievement in line with previous research. The on-sequence reformed course was found to have more equity in achievement between sexes. Possible sources of that improvement from the traditional course were investigated, and the weighting of different course components in the overall course grades was found to be a critical piece in the reformed course's more equitable outcomes. Though our results are promising in terms of offering a recommendation that may aid in advancing equity between sexes, our results indicate that the educational reforms made fell short in mitigating the pervasive racial/ethnic inequities found in achievement and performance measures.

Chemical scientists and engineers are interested in controlling chemical processes to attain specific goals, from synthesizing a desired substance to hindering a particular transformation. Nevertheless, students typically have few opportunities to develop the understandings and practices that are required to effectively engage in chemical control. In this study, we investigated similarities and differences among individuals with different levels of expertise in chemistry in the ways they think about how to control and act to control a chemical reaction. Our findings revealed that all types of study participants engage in the manipulation of similar control parameters but with different approaches and purposes. In particular, we observed a shift from a focus on physical to chemical factors, from experienced-based to model-based reasoning, from qualitative to quantitative methods, and from trial-and-error to guided investigation approaches in the thinking and acting of the more novice to the more expert participants in our study.

Chemical thinking is a powerful tool for making sense of the material world and acting on it. But developing competence in chemical thinking may be challenging for students as it varies in several dimensions. This contribution seeks to guide and help chemistry educators in the design of learning experiences that support the development of "multifaceted chemical thinking" by identifying and describing different dimensions along which chemical reasoning may vary, and by discussing how to foster such a competence. In particular, the article elaborates on how chemical reasoning varies along six dimensions named Granularity, Dimension, Frame, Basis, Mode, and Focus.

Evaluation of student written work during summative assessments is an important task for instructors at all educational levels. Nevertheless, few research studies exist that provide insights into how different instructors approach this task. In this study, we characterised variation in chemistry instructors' approaches to the evaluation and grading of different student responses to conceptual questions in general chemistry summative assessments, and analysed the correlation of such variations with assigned grades. Our results revealed differences in the approaches followed by instructors along various dimensions, such as their focus of attention (e.g., knowledge vs. reasoning), the construction and use of a rubric to evaluate student work, and the extent to which instructors engaged in building inferences about student understanding. Most instructors, however, were consistent in the approaches they individually followed when analyzing different student responses. Differences in approaches along some dimensions correlated to assigned grades, but relevant dimensions differed for novice and experienced instructors (e.g., adopting an inferential "versus" a literal stance had a significant correlation with the grades assigned by experienced instructors but not by novice ones). The results of our study provide insights into strategies for the professional development of college instructors such as asking instructors to critically reflect on how the decisions they make along multiple dimensions during the grading process can affect the outcome.

The periodic table allows students to easily understand the chemical elements and predict the behavior of theoretical yet undiscovered new elements. Many memorization techniques have been used for learning the periodic table, yet serious games (i.e., designed for a primary purpose other than pure entertainment) have been underexplored to complement or even replace such memorization techniques. Since CHEMMEND, an existing physical card game, was found to assist with learning the periodic table, we explore the potential of E-CHEMMEND, a digital version of the game as an aid to memorize the group and period numbers of the elements. E-CHEMMEND is a single-player serious game to explore the effect of four different game conditions involving two experimental factors that account for different educational scenarios. The first factor investigates the role of playing through levels of increasing difficulty versus playing with all elements from the very beginning. The second factor investigates the role of displaying the group and period numbers of the chemical element along with its symbol versus only displaying the element symbol. Preliminary results show that E-CHEMMEND is perceived as more enjoyable when the group and period numbers are displayed. In contrast, the game is found to better assist learning when this information is hidden and levels are shown. Taken together, our results suggest that a variety of educational purposes can be accommodated with a range of game settings. Ultimately, the design rationale and the lessons learned while testing E-CHEMMEND will be valuable for chemistry instructors and education researchers. A desktop-based Windows executable version of the game is available at http://www.chemmend.uji.es/game.

Chemistry faculty instructors (FIs) and graduate student instructors (GSIs) regularly engage in the evaluation and grading of student responses in formal formative and summative assessments. In this study, we identified dimensions of variation in these instructors' approaches to the evaluation and grading of students' answers. Using qualitative methods of research, we conducted individual interviews in which participating chemistry FIs and GSIs were asked to evaluate and grade the same set of students' responses to a typical exam prompt and justify their decisions. Our results indicate that an observed variability in assigned grades emerged from the complex interaction of explicit and implicit decisions made and preferences manifested along various dimensions. Our findings suggest avenues for the professional development of chemistry instructors that can help reduce grading variability.

Formative assessment has been proven to be highly effective in improving student understanding. Nevertheless, many instructors struggle to engage in this practice, particularly when working in large-enrollment classrooms. To facilitate and foster the implementation of formative assessment in chemistry courses, undergraduate students at our institution have been trained to gather and analyze formative assessment data in real time in different classrooms. These "Learning Researchers" generate written reports that instructors use to inform their practice. In this article, we characterize what learning researchers involved in this project tended to notice in their observations and the nature of the interpretations that they built. The findings of our qualitative study provide insights into the affordances and potential constraints of using undergraduate students to collect and interpret formative assessment data to inform instructional practices in large-classroom environments.

The ability to build mechanistic explanations of natural phenomena is highly valued in all scientific disciplines, including chemistry. In this paper, we summarize the results of a qualitative study designed to characterize the nature of the mechanistic explanations built by college General Chemistry students when analyzing a physical process involving energy transfer between parts of a system at different temperatures, and a chemical process involving energy transformation and transfer due to chemical bonding. Prior studies have mostly focused on eliciting "what" students think happens in terms of energy transfer when chemical bonds break or form (e.g., energy is absorbed or released) and in this investigation we provide insights into their reasoning about "how" and "why" it happens. Our findings reveal that many students struggle to build sound mechanistic explanations for energy transfer between objects at different temperatures and for energy transformation and transfer during the formation of chemical bonds.

Formative assessment is an important component of teaching as it enables teachers to foster student learning by uncovering, interpreting, and advancing student thinking. In this work, we sought to characterize how experienced chemistry teachers notice and interpret student thinking shown in written work, and how they respond to what they learn about it. Drawing on qualitative methods from different educational fields, we analyzed data collected during focus groups of middle and high school teachers. Using a "chemical thinking" lens, teachers' formative assessment practices were characterized as descriptive vs inferential in noticing, evaluative vs sense-making in interpreting, and directive vs responsive in acting. Four major patterns emerged in teachers' interpreting of student thinking and proposed acting. These patterns affected the diversity of ideas that teachers noticed in student work. Ways of using the findings are offered for chemistry teachers wishing to examine and diversify their own noticing practices, and for professional development efforts in this area.

The COVID-19 pandemic has fundamentally changed many aspects of our world including the way we teach chemistry. Our emergence from the pandemic provides an opportunity for deep reflection and intentional action about what we teach, and why, as well as how we facilitate student learning. Focusing on foundational postsecondary chemistry courses, we suggest that we cannot simply return to "normal" practice but need to design and implement new ways of teaching and learning based on fundamentally reimagined learning outcomes for our courses that equip students for life after the rupture they have experienced. We recommend that new learning objectives should be guided both by an analysis of existing global challenges and the types of understandings and practices needed to confront them, and by research-based frameworks that provide insights into important areas of knowledge, skill, and attitude development. We identify a core set of competencies along three major dimensions (crosscutting reasoning, core understandings, and fundamental practices) that we believe should guide the design, implementation, and evaluation of chemistry curricula, teaching practices, and assessments in foundational courses for science and engineering majors. The proposed framework adopts systems thinking as the underpinning form of reasoning that students should develop to analyze and comprehend complex global systems and phenomena.

The decisions and actions that chemistry educators make regarding why, what, how, and when to teach certain content or implement a specific instructional activity are often guided, but also constrained, by explicit or implicit "didaktik models". These types of models direct our attention and actions when designing curricula, planning for instruction, or assessing the learning process. They also give educators a professional language when talking or reflecting about teaching and learning. When used systematically, didaktik models support the implementation of research-based instructional practices and are helpful in the professional development of educators. In this essay, we describe, analyze, and discuss the nature and utility of didaktik models in chemistry education and argue that it is critical for chemistry educators to recognize and reflect on the types of models that guide their work.

Understanding how chemistry teachers' interventions shape the reasoning that students express after a lesson is critical to support prospective and in-service teachers as they work with students' ideas in the classroom. In this qualitative research study, we analysed changes in the reasoning expressed by 10th grade students in a Chilean school in their written explanations about freezing point depression before and after a lesson on the topic. We also investigated how the teacher's interventions shaped the type of reasoning expressed by participating students. Our findings revealed significant shifts in the types of explanations generated after the lesson. A significant number of students transitioned from relational to simple causal reasoning in their pre- and post-lesson explanations. After the lesson most of the explanations were based on the activities of one or more of the system's entities. Analysis of teacher-student interactions during the observed lesson suggests that the teacher's mediation played a central role in the shift towards simple causal reasoning with centralized causality that was observed. The teacher in our study was more skilled at eliciting students' ideas than at helping students develop them with proper scaffolding. Thus, the observed classroom talk could not be considered as accountable talk, as most of the key ideas were introduced, selected, or reshaped by the teacher.

A study was made of different emotions that prospective primary school teachers report with respect to science subjects, when they were pupils, and during their practice teaching, taking into account the variables gender and the specialty they studied in the secondary education. The study consisted of a questionnaire completed by 63 primary education students at the University of Extremadura, Spain. The results show a great difference between the emotions related to the subjects of physics/chemistry and the nature sciences (biology/geology). The scientific subject influences the emotions of pre-service primary teachers, both in learning and teaching. In physics and chemistry, the emotions are mostly negative. While in nature sciences they are very positive. In nature sciences, there is a correlation between the emotions felt as secondary school pupils learning science and those they feel as teachers. In physics and chemistry, there is a correlation in the women between the emotions felt as secondary school pupils learning science and those they feel as teachers, but not in the men. The memory of their emotions in learning science at school is more negative than in teaching science during their teaching practice, except in nervousness in physics/chemistry. By gender, men declared a greater predilection for science content than women, with more of them describing such feelings as sympathy or confidence. The results highlight the influential role that emotions play throughout the professional growth of future primary teachers. (Contains 2 tables and 6 figures.) [An earlier version of this article was presented as a paper at ESERA Conference 2009, Istanbul, Turkey, August 31st-September 4th. This work was financed by Research Project of the Ministry of Education and Science (Spain) and European Regional Development Fund (ERDF).]

Misconceptions of chemistry and chemical engineering university students concerning instrumental analysis have been established from coordinated tests, tutorial interviews and laboratory lessons. Misconceptions can be divided into: (1) formal, involving specific concepts and formulations within the general frame of chemistry; (2) operational/topical, dealing with specific capabilities, problems and operations in chemistry; (3) methodological, associated to peculiar methods of analytical chemistry and data treatment; and (4) social, regarding the relation of analytical data with the social frame. Such misconceptions define a non-structured view of analytical methods, procedures and protocols related with analytical instrumentation. Instruments are frequently viewed as an autonomous, error-free black box providing non-structured data with no need of calibration or control, whereas weak relationships are established between data and aims along the analytical process. (Contains 7 tables and 8 figures.) [Financial support for this paper was provided by the University of Valencia research project "Desarrollo de herramientas para el diagnostico y evaluacion de errores conceptuales y metodologicos en la ensenanza de la Quimica instrumental."]

Understanding the nature of chemical thinking and action, as well as their application and impact on our world should be central goals of chemistry education at all educational levels. However, traditional school chemistry is still mostly focused on having students learn the body of declarative knowledge built over the years in the discipline. Achieving changes in curriculum and teaching practices in this context remains a challenging task. Studies in the history and philosophy of the discipline suggest that chemistry has unique characteristics that need to be recognised and considered in chemistry education. Many of these studies point to a pluralism in the discipline, and in the understanding of and about chemistry, that should be characterised and incorporated into our educational models. In this essay, we have attempted to build such a characterisation using conceptual profiles theory to propose a framework that can be used to enrich and support the thinking and action of chemistry teachers at all educational levels.

The central goal of this research study was to characterise the different types of reasoning manifested by high school chemistry students when building initial written explanations of a natural phenomenon. In particular, our study participants were asked to explain why a mixture of water and alcohol works as an antifreeze. Data collected in the form of written explanations were analysed using a mechanistic reasoning framework based on the characterisation of system components (e.g., entities, properties, activities, organisation) and paying attention to the causal models invoked by the participants in their explanations. Our analysis revealed that students at the same educational level construct a wide range of explanations for the same phenomenon that are indicative of different reasoning modes going from descriptive to relational to simple causal to emerging mechanistic. Although the explanations generated by students in our sample were not very sophisticated in terms of the causal models on which they relied, some participants were capable of generating mechanistic explanations using particulate models of matter. The framework for analysis introduced in this contribution can be of use to teachers and researchers in the characterisation of student reasoning.

In this essay, findings from research in science and chemistry education are used to describe and discuss progression in students' structure-property reasoning through schooling. This work provides insights into the challenges that students face to master this important component of chemical thinking. The analysis reveals that student reasoning is often guided by non-normative implicit schemas that are little affected by traditional instruction. These schemas prioritize chemical composition over molecular structure, and centralized causality over emergence in the explanation and prediction of the properties of substances. The types of components that students invoke to make sense of properties and phenomena may change with schooling, but the underlying reasoning persists. In general, learners assume that observed properties and behaviors are directly related to the types of atoms present in a system and determined by these individual atoms' inherent characteristics.

We present the results of a qualitative research study designed to explore differences in the types of reasoning triggered by information presented to chemistry students in two different formats. One group of students was asked to analyze a sequence of images designed to represent critical elements in the explanation of a target phenomenon. Another group of students was asked to analyze an illustrated text that introduced core concepts and ideas needed to understand the same phenomenon. Our study revealed major differences but also important similarities in student reasoning under the two conditions. Analyses of images led to more descriptive and limited accounts of the phenomenon than the analyses of text. However, these latter analyses often were plagued by conceptual confusions. Mechanistic explanations built under the two conditions frequently invoked a single causal factor as responsible for the phenomenon. Probabilistic effects were consistently neglected in these explanations.

One of the central goals of modern science and chemistry education is to develop students' abilities to understand complex phenomena, and productively engage in explanation, justification, and argumentation. To accomplish this goal, we should better characterise the types of reasoning that we expect students to master in the different scientific disciplines. This analysis is needed to support the design of instructional tasks, teaching strategies, and assessments that foster those ways of thinking. This essay contributes in this direction by characterising the major types of rationales built and applied by experts when analysing chemical systems and processes. The term 'chemical rationale' is used to refer to any product of reasoning that uses chemical knowledge to build explanations, justifications or arguments. Three main types of rationales are identified and discussed: Phenomenological, Mechanical, and Structural. Difficulties associated with learning how to build each type of rationale are highlighted, and implications for research and practice of this other chemistry 'triplet' are discussed.

Calls for educational reform in undergraduate STEM education have become more prominent in recent years, particularly in introductory/foundational courses. Such reform efforts were initiated 10 years ago in the general chemistry program at the University of Arizona. In this contribution, we describe the major successes and challenges encountered during the full implementation of a new chemical thinking curriculum across all sections of a large course serving thousands of science and engineering majors every year. Besides describing the goals and structure of the alternative curriculum, as well as its impact on student learning, our work seeks to provide insights into institutional conditions, resources, and constraints that foster or hinder the success of major educational reforms.

With the final objective of using computational and chemometrics tools in the chemistry studies, this paper shows the methodology and interpretation of the Principal Component Analysis (PCA) using pollution data from different cities. This paper describes how students can obtain data on air quality and process such data for additional information related to the pollution sources, climate effects, and social aspects over pollution levels by using a powerful chemometrics tool such as principal component analysis (PCA). The paper could also be useful for students interested in environmental chemistry and pollution interpretation; this statistical method is a simple way to display visually as much as possible of the total variation of the data in a few dimensions, and it is an excellent tool for looking into the normal pollution patterns.

Formative assessment has been defined as the process "to recognize and respond to student learning to enhance that learning during the learning." Formative assessment helps teachers identify strengths and weaknesses in their students' understanding, focuses students' attention on relevant information and ideas, and provides scaffolds that guide and support student progress (NRC 2011). Formative assessment is an ongoing process in which teachers typically engage in multiple cycles of: (1) eliciting students' ideas; (2) noticing the substance of students' thinking; (3) interpreting to make sense of students' ideas, and (4) acting to guide and support student learning. How teachers approach formative assessment influences students' conceptual understanding, as well as their attitudes, motivation, and effort, particularly among underperforming learners. Research indicates that meeting the new vision of the "Next Generation Science Standards" requires shifting teaching practices from more prescriptive approaches that emphasize "discrete facts with a focus on breadth over depth" toward more responsive approaches that provide "time for students to engage in scientific investigations and argumentation and to achieve depth of understanding of the core ideas presented." In each of the four dimensions listed, a teacher's practices can be characterized along a continuum from more prescriptive to more responsive. This article, using results from investigations of chemistry teachers' practices, suggests ways to implement more responsive approaches to formative assessment in the science classroom.

This study reports the use of data mining tools in order to examine the influence of the methodology used in chemistry lab classes, on the weight attributed by the students to the lab work on learning and own motivation. The answer frequency analysis was unable to discriminate the opinions expressed by the respondents according to the type of the teaching methodology used in the lab classes. Conversely, the data mining approach using "k"-means clustering models, allowed a deeper analysis of the results, "i.e.," enabled one to identify the methodology to teach chemistry that, in students' opinion, is important for learning chemistry and increasing their motivation. The sample comprised 3,447 students of Portuguese Secondary Schools (1,736 in the 10th grade; 1,711 in the 11th grade). The "k"-means Clustering Method was used, with "k" values ranging between 2 and 4. The main strengths of this study are the methodological approach for data analysis and the fact that the sample was formed by students with different school careers that enables the use of the individual as the unit of analysis.

The central goal of this study was to characterize major patterns of reasoning exhibited by college chemistry students when analyzing and interpreting chemical data. Using a case study approach, we investigated how a representative student used chemical models to explain patterns in the data based on structure-property relationships. Our results elicited various reasoning challenges: undifferentiation of concepts, overreliance on surface explicit features, oversensitivity to contextual features, unconstrained application of ideas, hybridization of chemical and intuitive knowledge, and overreliance on nonmechanistic explanatory schemas. Our findings also revealed several affordances in student thinking: cognitive flexibility, responsiveness to probing and scaffolding, rich knowledge base, and pragmatism in the search for explanations. Our investigation provides insights into curriculum design and teaching and assessment strategies that can better leverage students' cognitive resources to scaffold learning.

Making decisions about the production and use of chemical substances is of central importance in many fields. In this study, a research team comprising teachers and educational researchers collaborated in collecting and analyzing cognitive interviews with students from 8th grade through first-year university general chemistry in an effort to map progression in students' ability to make decisions about the consequences of using and producing chemicals. Study participants were asked to explain their reasoning about which fuel would be best to power a small vehicle. Data were analyzed using a "chemical thinking" lens to characterize conceptual sophistication and complexity of reasoning. Results revealed that most reasoning was intuitive in conceptual sophistication and relational in argumentative nature, driven by the consequences of using the fuels based on their composition. Implications are discussed for the design of learning experiences and assessments that better support students' development of decision-making using chemical knowledge.

The topic of acid-base chemistry is one of the oldest in general chemistry courses and it has been almost continuously in academic discussion. The central purpose of documenting the knowledge and beliefs of a group of ten Mexican teachers with experience in teaching acid-base chemistry in high school was to know how they design, prepare and organize their classes inside and outside the classroom, from which a set of teaching-learning sequences will be developed, essentially to train new teachers. We decided to document Pedagogical Content Knowledge (PCK), by means of two methodological tools from Loughran, Mulhall and Berry: Content Representation (CoRe), and Pedagogical and Professional experience Repertoire (PaP-eR). In this article, we relate only the first of these tools. It was also important to document concepts, skills and attitudes, so we have made the analysis based on these three items. The main finding was to construct a Canonical PCK including the central concepts of pH and strength in the topic of acid-base chemistry from the main phrases included in the Content Representation answered by those outstanding Mexican teachers. We chose the topic of "acid-base chemistry" because there are numerous examples of its importance related to sustainability (among them acid rain or acidification of oceans), everyday issues (including stomach acidity, antacids, health troubles with the pH of blood and urine), or problems with the longevity of books related to the acidity of paper. Also, it is of fundamental importance because the students often present many alternative conceptions about it.

Research in science education has revealed that many students struggle to understand chemical reactions. Improving teaching and learning about chemical processes demands that we develop a clearer understanding of student reasoning in this area and of how this reasoning evolves with training in the domain. Thus, we have carried out a qualitative study to explore students reasoning about chemical causality and mechanism. Study participants included individuals at different educational levels, from college to graduate school. We identified diverse conceptual modes expressed by students when engaged in the analysis of different types of reactions. Main findings indicate that student reasoning about chemical reactions is influenced by the nature of the process. More advanced students tended to express conceptual modes that were more normative and had more explanatory power, but major conceptual difficulties persisted in their reasoning. The results of our study are relevant to educators interested in conceptual development, learning progressions, and assessment.

Chemistry teaching has traditionally been weakly connected to everyday life, technology, society, and history and philosophy of science. This article highlights knowledge areas and perspectives needed by the humanistic (and critical-reflexive) chemistry teacher. Different humanistic approaches in chemistry teaching, from simple contextualization to socioscientific orientations to multifaceted problematization, are discussed. The latter is crucial for "critical chemistry teaching", which includes both problematized content knowledge "in" chemistry and problematized knowledge "about" chemistry and chemistry education (about the nature of chemistry, its role in society, and the way it is communicated inside and outside the classroom). We illustrate how various facets of chemistry knowledge for teaching can be used to characterize different levels of complexity in the integration of the human element into chemistry education.

Deep knowledge of the periodic table is one of the most important keys to understand the basic principles of Chemistry. Memorizing the elements of the groups and periods is one of the most commonly used strategies to learn the position of each element in the periodic table; nevertheless, it is a hard task for most students. The use of card games can represent a useful alternative to teach some chemical aspects. Here, we present "ChemMend," a new chemical card game that will allow chemistry students to obtain a good ability in the periodic table. This game attracts the attention of the students, and it allows them to review mentally the period and group while playing; this learning is a consequence of the game. The "ChemMend" game introduces and explores the periodic table in the classroom.

Science education frameworks and standards play a central role in the development of curricula and assessments, as well as in guiding teaching practices in grades K-12. Recently, the National Research Council published a new Framework for K-12 Science Education that has guided the development of the Next Generation Science Standards. In this paper, we discuss what we see as critical gains, losses, and missed opportunities in the representation of chemistry in these new documents compared to the previous National Science Education Standards. The goal is to facilitate the comparative analysis of these two documents from a chemistry perspective, and elicit issues that we judge demand greater discussion and reflection among chemistry educators.

Background: Until recently, the affective components of education had long been undervalued. Today, one finds ever more studies on cognitive and affective interrelationships that are lending support to the idea that affect and cognition are best understood when viewed as independent and complementary mental functions. Purpose: The present work analyses the emotions of prospective secondary education teachers, distinguishing them by gender, in relation to the teaching of Biology, Geology, Physics and Chemistry in order to contribute to designing subsequent interventions targeted at improving science teachers' occupational health. Sample: The total sample consisted of 178 students (53 male and 125 female) of the post-graduate teaching certificate course at the University of Extremadura, all of whom were prospective secondary school teachers. We also worked with a sub-sample of 66 Science and Engineering graduates (33 male and 33 female). Design and Methods: A questionnaire was prepared that includes items on each of the emotions that the prospective teacher might feel when teaching the science content of the proposed courses. The chi-squared test was used to determine whether a relationship exists between emotions and the variable gender when it came to their teaching Biology, Geology, Physics and Chemistry at the compulsory secondary education level. Results: The results showed that the male teachers more frequently report positive emotions than the female. The latter manifested an increase in negative emotions in teaching Geology, Physics and Chemistry content. And the study of the sub-sample showed positive emotions are more frequently reported than negative ones in all four subjects, with this being particularly so in Biology. Conclusions: The study of emotions is vital in the educational formation of prospective secondary teachers. These students will soon face day-to-day life in the classroom, and many of them, especially the women, declare themselves to be emotionally vulnerable, since they describe themselves as experiencing stronger negative emotions. It is essential to provide prospective secondary teachers with a program of support and monitoring during their teaching practice so as to foster awareness of their emotions towards science and its learning. The aim must be to enhance their capacity for self-regulation and control to change those emotions, and to consolidate healthy habits.

Given the diversity of materials in our surroundings, one should expect scientifically literate citizens to have a basic understanding of the core ideas and practices used to analyze chemical substances. In this article, we use the term 'chemical identity' to encapsulate the assumptions, knowledge, and practices upon which chemical analysis relies. We conceive chemical identity as a core crosscutting disciplinary concept which can bring coherence and relevance to chemistry curricula at all educational levels, primary through tertiary. Although chemical identity is not a concept explicitly addressed by traditional chemistry curricula, its understanding can be expected to evolve as students are asked to recognize different types of substances and explore their properties. The goal of this contribution is to characterize students' assumptions about factors that determine chemical identity and to map how core assumptions change with training in the discipline. Our work is based on the review and critical analysis of existing research findings on students' alternative conceptions in chemistry education, and historical and philosophical analyses of chemistry. From this perspective, our analysis contributes to the growing body of research in the area of learning progressions. In particular, it reveals areas in which our understanding of students' ideas about chemical identity is quite robust, but also highlights the existence of major knowledge gaps that should be filled in to better foster student understanding. We provide suggestions in this area and discuss implications for the teaching of chemistry.

Dominant educational approaches in chemistry focus on the learning of somewhat isolated concepts and ideas about chemical substances and reactions. Reform efforts often seek to engage students in the generation of knowledge through the investigation of chemical phenomena, with emphasis on the development and application of models to build causal explanations and predict outcomes. However, chemistry has been characterized as a technoscience that blends scientific pursuit and technological goals. Besides searching for explanations, our discipline also involves the design of substances and processes to address relevant problems, as well as the evaluation of social, economic, and environmental benefits, costs, and risks associated with chemical knowledge and products. In order to develop authentic curricula, instruction, and assessments that are better aligned with the core goals and practices of chemistry, we need to understand how students' "chemical thinking" progresses over time. We define chemical thinking as the development and application of chemical knowledge and practices with the main intent of analyzing, synthesizing, and transforming matter for practical purposes. In this paper we present a blueprint of a theoretically sound and evidence-based foundation for an educational framework centered on the idea of chemical thinking. Our investigations are focused on the development of a learning progression that describes likely pathways in the evolution of students' chemical thinking with training in the discipline from grade 8 (age 13-14) through 16 (undergraduate completion).

Chemistry students and teachers often explain the chemical reactivity of atoms, molecules, and chemical substances in terms of purposes or needs (e.g., atoms want or need to gain, lose, or share electrons in order to become more stable). These teleological explanations seem to have pedagogical value as they help students understand and use abstract chemical models. They may, however, become a roadblock in developing mechanistic understandings of the structure and properties of chemical systems. I explore the explanatory preferences of college students with different levels of training in chemistry to determine the extent to which they prefer teleological explanations over causal explanations. Major results revealed a strong preference at all the targeted educational levels for explanations that invoke intentionality as a driver for chemical reactivity. I discuss the educational implications of these findings and invite chemistry educators to reflect on these issues.

Teaching reform efforts in chemistry education often involve engaging students in small-group activities of different types. This study focused on the analysis of how activity type affected the nature of group conversations. In particular, we analyzed the small-group conversations of students enrolled in a chemistry course for nonscience majors. Group work in this course was designed and facilitated by preservice teachers enrolled in a science teaching methods class. Our results suggest that the types of activities in which students were engaged influenced the extent to which group talk focused on content-related issues. In particular, activities that asked students to compare and contrast different systems, different ideas, or predicted and actual behaviors were often associated with higher student engagement in constructing, transforming, and applying knowledge to make sense of concepts and ideas discussed in class.

Diverse implicit cognitive elements seem to support but also constrain reasoning in different domains. Many of these cognitive constraints can be thought of as either implicit assumptions about the nature of things or reasoning heuristics for decision-making. In this study we applied this framework to investigate college students' understanding of structure-property relationships in the context of chemical reactivity. The ability to understand and apply structure-property relationships to explain the behavior of physical, chemical, and biological systems is a core competence that many science and engineering majors are expected to develop. Core findings were derived from semi-structured interviews based on a ranking task. Study participants relied on intuitive, spurious, and valid assumptions about the nature of chemical entities in building their responses. In particular, many of students appeared to conceive chemical reactions as macroscopic reassembling processes thought to be more favored the easier it seemed to break reactants apart or put products together. Students also expressed spurious chemical assumptions based on the misinterpretation and overgeneralization of chemical ideas. Reasoning heuristics for decision-making also played a significant role in the construction of answers to ranking questions. Specifically, interviewees demonstrated strong over-reliance on variable reduction strategies and recognition memory in their reasoning. Our findings reveal the need for educational approaches that more effectively affect the conceptual sophistication and depth of reasoning about structure-property relationships of college students. Our research framework provides a productive approach for the analysis of student reasoning in scientific domains. (Contains 3 tables.)

The chemistry knowledge that we want our students to develop is rich, complex, and multifaceted. However, some teachers and instructors at the secondary school and college levels approach it in rather rigid and unidimensional ways. The central goal of this contribution is to describe and discuss 10 different complementary perspectives or "facets" from which chemistry content in introductory courses can be analyzed. This multidimensional view may help chemical educators, particularly those who are new to the profession, enrich their understanding of chemistry as a teaching subject and open the path for diverse reconceptualizations of the chemistry curriculum.

Studies of the philosophy of chemistry over the past 15 years suggest that chemistry is a hybrid science which mixes scientific pursuits with technological applications. Dominant universal characterizations of the nature of science thus fail to capture the essence of the discipline. The central goal of this position paper is to encourage reflection about the extent to which dominant views about quality science education based on universal views of scientific practices may constrain school chemistry. In particular, we discuss how these predominant ideas restrict the development of chemistry curricula and instructional approaches that may better support the learning of the ideas and practices that studies of the philosophy of chemistry suggest are at the core of the discipline. Our analysis suggests that philosophical studies about the nature of chemistry invite us to transgress traditional educational boundaries between science and technology, inquiry and design, content and process, and to reconceptualize school chemistry as a paradigmatic techno scientific subject. To support these changes, chemical education researchers should expand the scope of their investigations to better understand how students and teachers reason about and engage in more authentic ways of chemical thinking and doing.

The central goal of our exploratory study was to investigate differences in college chemistry students' interactions during lab experiments with different levels of inquiry. This analysis was approached from three major analytic dimensions: (i) functional analysis; (ii) cognitive processing; and (iii) social processing. According to our results, which were based on the qualitative analysis of direct observations of different groups of students working in general chemistry laboratories, experiments that involved higher levels of inquiry were associated with an increase in the frequency of episodes in which students engaged in proposing ideas versus asking and answering each others' questions. Higher levels of inquiry also favored episodes in which experimental work was approached in a more exploratory (versus procedural) manner. Increased levels of inquiry were also associated with more frequent episodes of domination in which a few students in a group directed the actions of others. In general, our results elicit trends and highlight issues that can help instructors identify strategies to better support and scaffold productive engagement in the laboratory. (Contains 3 figures and 2 tables.)

Gold nanoparticles (AuNPs) have a wide range of applications due to their optoelectronic properties. Particularly, biological synthesis of AuNPs highlights due to the advantages related to the environmental care and the stabilization provided by capping biomolecules during biosynthesis. The antimicrobial activity of AuNPs was reported, however, their activity against resistant structures such as bacterial endospores have not been evaluated. This work shows the extracellular biosynthesis of AuNPs using Epicoccum nigrum (Au1-8) throughout an ecofriendly, simple, and efficient method. Physicochemical characterization revealed that stable quasi-spherical AuNPs in a range size of 2 to 30 nm, with crystal structure and metallic Au0 composition were obtained. The AuNPs sporicidal activity against Bacillus subtilis endospores was evaluated by its exposure to 300 mg/L AuNPs during 48 h, which produced a decrease of 90.6% of the endospore germination. The analysis of the endospore-AuNP interaction by scanning electron microscopy (SEM) and infrared (IR) spectroscopy revealed injury of the endospore coat and lysis. These results are promising for the advance in the development of low-aggressive agents used for environmental decontamination regimens against pathogenic bacterial spores, or even as an alternative for the treatment of illnesses produced by endospore-former causative agents of food spoilage/poisoning and human diseases.

The central goal of the present exploratory study was to investigate the nature of the content-related interactions in study groups independently organized by college organic chemistry students. We were particularly interested in the identification of the different factors that affected the emergence of opportunities for students to co-construct understanding and engage in higher levels of cognitive processing. Our results are based on the analysis of "in situ" observations of 34 self-initiated study sessions involving over a 100 students in three academic semesters. The investigation revealed three major types of social regulation processes, teaching, tutoring, and co-construction in the observed study sessions. However, the extent to which students engaged in each of them varied widely from one session to another. This variability was mostly determined by the specific composition of the study groups and the nature of the study tasks in which they were engaged. Decisions about how to organize the study session, the relative content knowledge and conceptual understanding expressed by the participants, as well as the cognitive level of the problems that guided group work had a strong impact on the nature of student interactions. Nevertheless, group talk in the observed study groups was mostly focused on low-level cognitive processes. The results of our work provide insights on how to better support students' productive engagement in study groups. (Contains 4 tables.)

Using the responses to open questions, this qualitative study examines the personal metaphors expressed by prospective secondary education teachers, 46 science graduates and 41 economics graduates. The metaphors are classified into the four categories of Leavy, McSorley, and Bote: the behaviourist/transmissive, the cognitivist/constructivist, the situative, and the self-referential. The results showed most metaphors to fall into the behaviourist/transmissive category, followed by the cognitivist/constructivist, self-referential, and situative categories, although some teachers expressed metaphors framed in more than one category. Of the 129 metaphors detected in the study, only one, of a chemistry graduate concerning the equilibrium between reactants, was associated with the prospective teachers' specific undergraduate education. The rest were expressions of their overall vision of teaching and learning, regardless of the speciality. (Contains 2 tables and 1 figure.)