Submicroscopic Level Research Articles

Representational challenges in animated chemistry: self-generated animations as a means to encourage students’ reflections on sub-micro processes in laboratory exercises

A central aspect of learning chemistry is learning to relate observations of phenomena to models of the sub-microscopic level of matter, and hence being able to explain the observable phenomena. However, research shows that students have difficulties discerning and comprehending the meaning of the sub-micro level and its models, and that practical work in its traditional form fails to help students to discern the relation between observations and models. Consequently, there is a strong call for new teaching activities to address these issues. This paper emerges from a growing number of studies showing that learning is supported when students are set to cooperatively create their own multimodal representations of science phenomena. In this paper, we explore the approach of letting students create their own stop-motion animation as a means to explain observations during practical work. The students’ work of producing a phenomenon in the laboratory and creating an animation was recorded (audio–video) to capture students’ verbal and non-verbal interactions and use of resources. Data was analysed using a thematic content analysis with a deductive approach aimed at identifying the aspects of chemistry content that are being reasoned. The analysis showed that the task enabled students to engage in reasoning concerning both the observations and the sub-micro-level models, and how they relate to each other. The task also enabled students to reason about features of the representation that are needed to make sense of both the observational and sub-microscopic aspects of a phenomenon, as well as reflecting upon the meaning of a model.

CONNECTIONS INVOLVING THE USE OF CHEMICAL LANGUAGE AND UNDERSTANDING OF REDUCTION-OXIDATION REACTION

Understanding submicroscopic level, which requires in-depth chemistry knowledge, is difficult for students. The sample of the research consisted of 32 students, who performed a teaching-learning sequence of two electrochemical reactions. Eight of them were videotaped and their speech was transcribed and analyzed. The results indicated that students who used more chemical terms improved their understanding of the submicroscopic level. Talking more, in this case, showed no relation to learning directed to an instrumental understanding (focus on how). The use of more chemical terms enabled them to grasp a relational understanding (focus on why) and the predictive ability of new chemical phenomena. Keywords: chemical education, chemical terms, electrochemistry, relational understanding, submicroscopic level.

Learners’ Understanding of Chemical Equilibrium at Submicroscopic, Macroscopic and Symbolic Levels

Abstract It is not easy for secondary school learners to comprehend the concept of chemical equilibrium at the level of understanding. In this context, a feedback is important for the teachers to optimize their help to students in constructing this concept. We designed and tested sets of particularly prepared tasks, the solution of which reflects the depth of understanding of the basic concept in macroscopic, submicroscopic and symbolic representation. Difficulties in understanding the chemical phenomena and concepts do not result only from the existence of these three levels or from their explanation using abstract concepts, but also from the lack of interconnection between these representations. Consistent interconnection of these levels can lead to an internal conflict in students, and consequently to a more profound understanding of the concept or relationships between concepts at multiple levels of representation to understand them or to change the meaning of one to another. There is also a close connection with the aspect of memory, algorithmic and conceptual approaches to solving educational situations, which extends dimensionally and reinforces the need for a more comprehensive grasp of learners’ mastery of the given concept. The teacher cannot expect that the learners without intensive training, e.g., only by observing the macroscopic representation, can interpret the essence of the submicroscopic representation. Therefore, these aspects need to be consistently involved in the model of learners’ cognitive process early enough to apply them in the educational practice without any problems.

The Level of Mastery of the Concept of Chemical Reaction Rate by 9th Grade Students

Abstract In this paper, we focused on the results of research, which we have conducted to ascertain the knowledge of Slovak students who have just finished their lower secondary education concerning the topic of chemical reaction rate. The study was attended by a total of 320 15-year-old graduates of basic chemistry education belonged to several schools. Students’ knowledge was found through didactic test consisted of 1 item related to clustering and several two-level tasks. The results were analyzed in terms of deeper insight into the students’ understanding of the issue and students’ misconceptions were also identified. The findings related to the problems connected with acquiring the concept of chemical reaction rate, especially in relation to the students’ grasp the mentioned topic at submicroscopic, macroscopic and symbolic levels of representation were analyzed. We managed to investigate the students’ various difficulties associated with mentioned topic. Several problems were found. Students have a problem with understanding the basic term “chemical reaction rate”, relating it to bodies in motion, which they know from physics lessons and everyday life. They also have problems to distinguish and interconnect information at different levels of representation. Students often do not know which factors affect the rate of reaction and how. They do not understand the concepts of concentration and catalyst and do not distinguish the terms temperature and heat. Students’ knowledge is often only formal and lacks a real conceptual understanding of the problem. Their solving of problems does not go beyond the algorithmic level of solution and they are not able to solve tasks that are not typically school-related issues.

Contribution of Logical Thinking Ability to Students’ Achievement in Three Level of Representations in Chemical Dynamic Materials

This research aims to explore information about the profile of the ability of logical thinking of high school students and its effect on student achievement on three levels of representation of chemical dynamics material. This research uses a non-experimental as research design in form of survey. This research involving 242 persons of 11 grade high school students at Ketapang Regency, West Borneo Province. Sampling is done by purposive sampling as a sampling method. There are two instruments in this research, first is Test of Logical Thinking and second is Test of three levels of representations that including 25 multiple choice tests which consist of three levels of representations such as macroscopic, submicroscopic, and symbolic levels. The material raised in this test is chemical dynamics material, including the concepts of reaction rates and chemical equilibrium. The research results is based on the statistically tested findings using the Pearson correlation test, it was found that logical thinking ability had a significant effect on macroscopic, submicroscopic, and symbolic with correlation coefficients of 0.352, 0.684, and 0.564, and significance values is less than 5% each of them.

Neon is a gas and has two rings – Separating the macroscopic and submicroscopic level of the periodic table

AbstractEs wird im Chemieunterricht nicht immer klar dargelegt, ob das besprochene Thema auf der makroskopischen oder auf der submikroskopischen Ebene abgehandelt wird. Auch in den eingesetzten Lernmaterialien, wie beispielsweise in den Versionen des Periodensystems der Elemente, die in Schulbüchern dargestellt sind, werden die Ebenen häufig miteinander vermischt. Dies kann für Schülerinnen und Schüler ein großes Lernhindernis darstellen. Der Artikel zeigt an einer Fallstudie die Lernschwierigkeiten von Schülerinnen und Schülern bei der Verwendung eines solchen Periodensystems bei der Erarbeitung des Atombaus auf. Als ein möglicher Weg zur Vermeidung der dargelegten Verständnisschwierigkeiten wird die Verwendung von zwei Periodensystemen zur Diskussion gestellt, die die unterschiedlichen Betrachtungsebenen explizit trennen.

The application of PhET simulation to teach gas behavior on the submicroscopic level: secondary school students’ perceptions

ABSTRACT Background: A multimedia software designed as a Computer-Assisted Scaffolding system was used to teach gas behavior on the submicroscopic level using Physics Education Technology Project (PhET) simulation. PhET is a set of interactive, research-based science and mathematics online simulations (https://phet.colorado.edu/). Purpose: The purpose was to investigate secondary school students’ perceptions of the simulation-based learning system and how it supported their cognitive processing of chemistry target concepts. Identifying its most (and least) helpful features and instructional strategies was also an objective of this study. Simulation-based learning system description: The Computer-Assisted Scaffolding system combined with the PhET simulation (Program) were meant to facilitate learners’ conceptual understanding of gas behavior on the submicroscopic level, which would serve as a foundation for learning gas laws on the macroscopic and symbolic level. Chemistry target concepts included causes for gas pressure, relationship between gas pressure and volume/temperature changes, and relationship between gas pressure and the number of particles. Sample: One hundred and fourteen secondary school students participated in this study as part of their science curriculum. Design and methods: Data on the students’ perceptions of the overall learning experience and specific Program features were collected and analyzed. Students responded to three open-ended questions and provided ratings of the Program features, such as pop-up explanations, images, model explorations, guiding questions, diagrams and feedback. They used a paper-based survey that was administered during the last 8 min of class. Results: The results provide preliminary evidence of the benefits of this approach in chemistry education. For instance, the changing variables in the simulation helped students understand gas behavior, the multiple images and working with the simulation lab helped students visualize gas behavior, and the design of the system made it easy for students to understand gas behavior on the submicroscopic level. Conclusions: The vast majority of the students reported a positive learning experience and described it as worth spending their time.

PCR-based detection of Plasmodium falciparum in saliva using mitochondrial cox3 and varATS primers

BackgroundSampling of saliva for diagnosing Plasmodium falciparum infections is a safe, non-invasive alternative to sampling of blood. However, the use of saliva presents a challenge because lower concentrations of parasite DNA are present in saliva compared to peripheral blood. Therefore, a sensitive method is needed for detection of parasite DNA in saliva. This study utilized two recently reported “ultra-sensitive” PCR assays based on detection of the P. falciparum mitochondrial cox3 gene and the multi-copy nuclear varATS gene. The ultra-sensitive assays have an advantage over standard 18S rRNA gene-based PCR assay as they target genes with higher copy numbers per parasite genome. Stored saliva DNA samples from 60 Cameroonian individuals with infections previously confirmed by 18S rRNA gene PCR in peripheral blood were tested with assays targeting the cox3 and varATS genes.ResultsOverall, the standard 18S rRNA gene-based PCR assay detected P. falciparum DNA in 62% of the stored saliva DNA samples, whereas 77 and 68% of the samples were positive with assays that target the cox3 and varATS genes, respectively. Interestingly, the ultra-sensitive assays detected more P. falciparum infections in stored saliva samples than were originally detected by thick-film microscopy (41/60 = 68%). When stratified by number of parasites in the blood, the cox3 assay successfully detected more than 90% of infections using saliva when individuals had > 1000 parasites/μl of peripheral blood, but sensitivity was reduced at submicroscopic parasitemia levels. Bands on electrophoresis gels were distinct for the cox3 assay, whereas faint or non-specific bands were sometimes observed for varATS and 18S rRNA that made interpretation of results difficult. Assays could be completed in 3.5 and 3 h for the cox3 and varATS assays, respectively, whereas the 18S rRNA gene assays required at least 7 h.ConclusionsThis study demonstrates that a PCR assay targeting the cox3 gene detected P. falciparum DNA in more saliva samples than primers for the 18S rRNA gene. Non-invasive collection of saliva in combination with the proposed cox3 primer-based PCR assay could potentially enhance routine testing of P. falciparum during disease surveillance, monitoring, and evaluation of interventions for malaria elimination.

The Accuracy of Macro-Submicro-Symbolic Language of Future Chemistry Teachers.

The present study is focused on the examination of language accuracy of future chemistry teachers in the macro-submicro-symbolic domain. Since the knowledge at the submicroscopic level is crucial for the understanding of chemical concepts and ideas, the aim of this study was to examine the accuracy of the language of future chemistry teachers while delivering chemical contents at this level. Within this objective, it was examined whether future chemistry teachers make a distinction between submicroscopic and macroscopic levels, as well as between submicroscopic and symbolic levels in their speech. Using qualitative methods of analysis, it was found that the majority of surveyed future chemistry teachers did not have the expected and necessary language accuracy within the examined domain. Most worrying were the attitudes of future chemistry teachers, who perceived the accurate expressions in the macro-submicro-symbolic domain as a redundant complication rather than a necessity.

Anatomy of the Le Fort I segment: Are arterial variations a potential risk factor for avascular bone necrosis in Le Fort I osteotomies?

PurposeOsteotomies of the Le Fort I segment are routine operations with low complication rates. Ischemic complications are rare, but can have severe consequences that may lead to avascular bone necrosis of the Le Fort I segment. Therefore the aim of this study was to investigate the blood supply and special arterial variants of the Le Fort I segment responsible for arterial hypoperfusion or ischemic avascular necrosis after surgery. Material and methodsThe arterial anatomy of the Le Fort I segment's blood supply using 30 halved human cadaver head specimens was analyzed after complete dissection until the submicroscopic level. In all specimens the arterial variants of the Le Fort I segment and also the arterial diameters measured at two points were evaluated. ResultsThe typical known vascularization pattern was apparent in 90% of all specimens, in which the ascending palatine (D1: 1,2 mm ± 0,34 mm; D2: 0,8 mm ± 0,34 mm) and ascending pharyngeal artery (D1: 1,3 mm ± 0,58 mm; D2: <0,4 mm) were both supplying the Le Fort I segment. However in 10% of all specimens, the Le Fort I segment was dependent on the ascending pharyngeal artery alone and the missing ascending palatine artery was replaced with the anterior branch of the ascending pharyngeal artery (D1: 1,9 mm ± 0,32; D2: 1,0 mm ± 0,3 mm). ConclusionThis study is the first description of a special type of arterial variation of the Le Fort I segment. The type of this arterial variation, its clinical relevance and potential consequences are explained. Individuals with this special arterial anatomy may clinically be at a high risk for hypoperfusion and avascular segment necrosis after surgery. An individualized operation plan may prevent ischemic complications in at-risk patients.

The effect of learning multimedia on students’ understanding of macroscopic, sub-microscopic, and symbolic levels in electrolyte and nonelectrolyte

This research aims to investigate the effect of learning multimedia on students’ understanding of macroscopic, sub-microscopic, and symbolic levels in electrolyte and nonelectrolyte topic. The quasi-experimental with one group pre-test post-test design was used. Thirty-five students were experimental class and another thirty-five were control class. The instrument was used is three representation levels. The t-test was performed on average level of 95% to identify the significant difference between experimental class and control class. The results show that the normalized gain average of experimental class is 0.75 (high) and the normalized gain average of control class is 0.45 (moderate). There is significant difference in students’ understanding in sub-microscopic and symbolic levels and there is not significant difference of students’ understanding in macroscopic level between experimental class and control class. The normalized gain of students’ understanding of macroscopic, sub-microscopic and symbolic in experimental class are 0.6 (moderate), 0.75 (high), and 0.64 (moderate), while the normalized gain of students’ understanding of macroscopic, sub-microscopic and symbolic in control class are 0.49 (moderate), 0.39 (high), and 0.3 (moderate). Therefore, it can be concluded that learning multimedia can help in improving students’ understanding especially in sub-microscopic and symbolic levels.

Student’s mental model, misconceptions, troublesome knowledge, and threshold concept on thermochemistry with DToM-POE

The purpose of this study is to obtain a profile of students' mental models, misconceptions, troublesome knowledge, and threshold concept on thermochemistry. The subjects in this study were 35 students. The method used in this research was descriptive method with instruments Diagnostic Test of Mental Model - Prediction, Observation, and Explanation (DToM-POE). The results showed that the students' ability to predict, observe, and explain ΔH of neutralization reaction of NaOH with HCl was still lacking. Most students tended to memorize chemical concepts related to symbolic level and they did not understand the meaning of the symbols used. Furthermore, most students were unable to connect the results of observations at the macroscopic level with the symbolic level to determine ΔH of neutralization reaction of NaOH with HCl. Then, most students tended to give an explanation by a net ionic equation or a chemical reaction equation at the symbolic level when explaining ΔH of neutralization reaction at the submicroscopic level. In addition, there are seven misconceptions, three troublesome knowledges, and three threshold concepts held by students on thermochemistry.

A study of primary school teachers’ conceptual understanding on states of matter and their changes based on their job locations (case study at Ambon island in Moluccas-Indonesia)

The research aims to describe primary school teachers’ conceptual understandings about states of matter and their changes. The method was descriptive which involved 15 primary school teachers from three different school locations. They were from urban school (CS1), sub-urban school (CS2), and rular school (CS3) at Ambon Island on 2016/2017 academic year. The research instrument was a multiple-choice test combined with both essay and confidence level of their answers. The test was used to measure teachers’ understanding levels about states of matter and their changes. They were macroscopic, sub-microscopic and symbolic levels. Teachers’ understanding levels were classified into following categorization, they were understand, partly understand, misconception, and do not understand. The results show that primary school teachers’ conceptual understanding is varied based on their job locations and primary school teachers’ level understanding. Generally, primary school teachers’ conceptual understandings at sub-urban location (CS2) are better than those of both of urban (CS1) and rular locations (CS3). The results suggest that teachers need improvement to make better primary school teachers’ conceptual understanding. It can be on the job training and in service training activities. We also need a further research in order to investigate the program effectiveness.

Why do Plants Wilt? Investigating Students’ Understanding of Water Balance in Plants with External Representations at the Macroscopic and Submicroscopic Levels

In order to understand water balance in plants, students must understand the relation between external representations at the macroscopic, microscopic, and submicroscopic levels. This study investigated how Slovenian students (N = 79) at the primary, secondary, and undergraduate tertiary levels understand water balance in plants. The science problem consisted of a text describing the setting, visualizations of the process occurring in a wilted plant stem, and five tasks. To determine students’ visual attention to the various elements of the tasks, we used eye tracking and focused on the total fixation duration in particular areas of interest. As expected, primary school students showed less knowledge and understanding of the process than the secondary school and university students did. Students with correct answers spent less time observing the biological phenomena displayed at the macroscopic and submicroscopic levels than those with incorrect answers, and more often provided responses that combined the macro-, micro-, and submicroscopic levels of thought. Learning about difficult scientific topics, such as the water balance in plants, with representations at the macroscopic and submicroscopic levels can be either helpful or confusing for learners, depending on their expertise in using multiple external representations, which is important to consider in biology and science education.

PEMANFAATAN BAHAN AJAR BERDASARKAN MULTI LEVEL REPRESENTASI UNTUK MELATIH KEMAMPUAN SISWA MENYELESAIKAN MASALAH KIMIA LARUTAN

Obeservation results indicated that students have difficulty of explaining chemical phenomena in league level representations (macroscopic, symbolic, and submicroscopic levels). The aim of the study was to obtain the information related to the influence of the use of teaching materials based on multi-level representation of the ability to solve the problem of solution materials of MAN students in Pidie Jaya. The teaching material contained of macroscopic, symbolic, and submicroscopic levels. Type this of research was quasi experiment which was tested in MAN Pidie Jaya. The study was conducted for four months through two stages namely: (1) observasion, (2) implementation. Implementation was carried out by using one-group pre-test design and post-test design. Instruments used consist of; observation sheets, note sheets of learning constraints, assessment and problem solving and representation sheets, and student response questionnaires. The data were obtained them analyzed descriptively. The results showed: (1) the ability chemical problem solving in MAN Ulim Pidie Jaya was increased from the average of 43 pre-test to 73 in post-test result this means that the teaching materials based on multi level representation used can train the ability to solve problem the solution, (2) the profile of students' ability movement during the learning process using teaching materials based on multi level representation increased at one to three meetings, this happened because the fourth meeting material characteristic was more complex, (3) based on student response to the using of teaching materials based on multi level representation was very helpful in training solve chemical problems of solution.

Application of cementitious composites in mechanical engineering

The paper presents the results of the development of composite fiber-reinforced concrete for use as basic parts of machine-tools and machines. It was revealed that the additions of fly ash and limestone significantly reduce the cracking of concrete. Thus, a clear relationship between the properties of concrete and the features of the structure of cement stone was revealed. The strength and crack resistance of concrete is increased due to an increase in the number of low-basic calcium hydrosilicates, as well as increased gel porosity and reduced capillary porosity (especially at the submicroscopic level).

The Role and Potential Dangers of Visualisation when Learning about Sub-Microscopic Explanations in Chemistry Education

The core of theory-driven chemistry education consists of the constant shift between the different representational domains of chemical thinking: the macroscopic, the sub-microscopic, and the symbolic domains. Because the sub-microscopic domain can neither be seen nor directly visualised, it requires specific forms of visualisation, i.e. pictures andanimations illustrating the model-based level of discrete particles, atoms, or molecular structures. This paper considers the central role visualisations play when learning about the model-based, sub-microscopic level, but it also reflects the dangers inherent in employing insufficiently examined, poorly considered, or even misleading visualisations. This is outlined using different examples taken from both textbooks for lower secondary chemistry education (for students aged 10 to 15) and from the internet. Implications for structuring and using sub-micro visualisations in chemistry education are also given.

Micro Imagination: Imagination with an Alternative Framework in a Chemistry Class

The curriculum for the 21st century must be futuristic, flexible and dynamic in order to produce learners with creative and critical thinking. One of the strategies to inculcate creative and critical thinking among students is to train and familiarize learners with the process of generating imagination in teaching and learning. The process of generating imagination corresponds to the characteristics of the subject itself which consists of abstract concepts and complexities. These concepts require students to use their imagination to illustrate concepts, where learners are usually difficult to achieve. Therefore, this study was carried out to identify alternative frameworks in the students’ imaginations of the concept of matter at submicroscopic level. A qualitative study with a descriptive study design is implemented to five secondary school students and ten students of institute of teacher education, aged from 18 to 25 years old. Guided imagery interviews and document analysis are used to collect data from selected students by purposive sampling. The data was analyzed using the grounded theory analysis strategy. The findings show that one of the alternative framework categories found in students’ imagination is micro imagination. The image of hydrogen gas is the ultimate framework of the micro imagination of the most generated structure by the students followed by hydrogen electrons, collision of hydrogen molecules and the formation of water molecules. In this regard, scientific imagination needs to be enhanced by students with emphasis on the concept of science with effective imagination so that students can master chemical concepts at the sub-microscopic level competently. From the conclusion, the implication of the study suggests that teachers should expose to the students the aspects of generative imagination during teaching and learning sessions so that the desired skills can be improved effectively.

The macroscopic, submicroscopic and symbolic level in explanations of a chemical reaction provided by thirteen-year olds

The aim of this research was to investigate whether pupils aged 13, at the end of their first year of studying chemistry, are capable of perceiving the macroscopic and the submicroscopic level of the previously learned contents on chemical reactions, and whether they relate them to the chemical equations (the symbolic representation). Another aim was to establish how much demonstration experiments contribute to a better linking of the mentioned levels. The research featured 69 pupils of the seventh grade from three primary schools. The pre-test was conducted, following which experiments were demonstrated, and the post- -testing was carried out in the end. After the intervention, a total of 12 pupils were interviewed about which aspects of chemical reactions they thought of based on the chemical equations. A statistically significant difference in two out of five requirements of the post-test, compared to the pre-test, indicate that the demonstration experiments may contribute to a better linking of three levels of representing chemical reactions. However, when one compares the pupils? answers in the test and in the interview, it can be observed that the correct answers in the test are not always based on understanding the concepts in connection with the chemical reaction.

Induction of immunity following vaccination with a chemically attenuated malaria vaccine correlates with persistent antigenic stimulation.

ObjectivesBlood stage malaria parasites attenuated with seco‐cyclopropyl pyrrolo indole (CPI) analogues induce robust immunity in mice to homologous and heterologous malaria parasites and are being considered for the development of a human vaccine. However, it is not understood how attenuated parasites induce immunity. We showed that following vaccination, parasite DNA persisted in blood for several months, raising the possibility that ongoing immune stimulation may be critical. However, parasites were not seen microscopically beyond 24 h postvaccination. We aimed to provide a mechanistic understanding of immune induction.MethodsMice were vaccinated with chemically attenuated Plasmodium chabaudi parasites. PCR and adoptive transfer studies were used to determine the presence of parasites and antigen in vivo. In other experiments, Plasmodium falciparum parasitised red blood cells were attenuated in vitro and RNA and antigen expression studied.ResultsWe show that blood transferred from vaccinated mice into naïve mice activates T cells and induces complete protective immunity in the recipient mice strongly suggesting that there is persistence of parasite antigen postvaccination. This is supported by the presence of parasite RNA in vaccinated mice and both RNA and antigen expression in P. falciparum cultures treated with CPI drugs in vitro. In addition, drugs that block parasite growth also prevent the induction of immunity in vaccinated mice, indicating that some growth of attenuated parasites is required for immune induction.ConclusionsAttenuated parasites persist at submicroscopic levels in the blood of mice postvaccination with the ability to activate T cells and induce ongoing protective immune responses.