Ute Harms

Content-Related Knowledge of Biology Teachers from Secondary Schools: Structure and learning opportunities

Teachers’ content-related knowledge is a key factor influencing the learning progress of students. Different models of content-related knowledge have been proposed by educational researchers; most of them take into account three categories: content knowledge, pedagogical content knowledge, and curricular knowledge. As there is no consensus about the empirical separability (i.e. empirical structure) of content-related knowledge yet, a total of 134 biology teachers from secondary schools completed three tests which were to capture each of the three categories of content-related knowledge. The empirical structure of content-related knowledge was analyzed by Rasch analysis, which suggests content-related knowledge to be composed of (1) content knowledge, (2) pedagogical content knowledge, and (3) curricular knowledge. Pedagogical content knowledge and curricular knowledge are highly related (rlatent = .70). The latent correlations between content knowledge and pedagogical content knowledge (rlatent = .48)—and curricular knowledge, respectively (rlatent = .35)—are moderate to low (all ps < .001). Beyond the empirical structure of content-related knowledge, different learning opportunities for teachers were investigated with regard to their relationship to content knowledge, pedagogical content knowledge, and curricular knowledge acquisition. Our results show that an in-depth training in teacher education, professional development, and teacher self-study are positively related to particular categories of content-related knowledge. Furthermore, our results indicate that teaching experience is negatively related to curricular knowledge, compared to no significant relationship with content knowledge and pedagogical content knowledge.

Preservice Teachers’ Professional Knowledge and Its Relation to Academic Self-Concept

We investigated the factorial structure of preservice teachers’ academic self-concept with regard to three domains of professional knowledge (content knowledge [CK], pedagogical content knowledge [PCK], and pedagogical/psychological knowledge [PPK]). We also analyzed the relation between preservice teachers’ academic self-concept and their professional knowledge. The sample consisted of N = 631 German preservice secondary teachers in biology and physics. To analyze the factorial structure of the academic self-concept, we applied confirmatory factor analyses (CFAs) and compared different models of complexity. Results confirmed that preservice teachers’ academic self-concept is empirically separable into CK, PCK, and PPK. Furthermore, the self-concept scales were positively related to the corresponding test scores in the professional knowledge domains. Our results revealed that preservice teachers’ academic self-concept is differentiated at a very early state of teacher education and reflects CK, PCK, and PPK performance. Hence, self-concept measures seem to provide an alternative means to assess preservice teachers’ professional knowledge in comparison with traditional performance measures.

Acquiring Knowledge about Biodiversity in a Museum--Are Worksheets Effective?.

This study examined the effectiveness of worksheets while learning about biodiversity in a natural history museum. Despite the frequent use of worksheets by school classes during out-of-school activities, their effectiveness in enhancing knowledge acquisition has been addressed by relatively few empirical studies. 148 Austrian grammar school students aged eleven to fifteen took part in the pre- and post-test questionnaire study which included a one-hour learning phase with worksheets in the museum. Results indicate a high learning effect from pre- to post-test. Further analyses show that worksheets contributed to knowledge gain, but this contribution is similar to that afforded by prior knowledge. The design of the worksheet tasks was also important. A closed task setting required the students to look for clearly defined solutions. This led to greater knowledge gains than open worksheet tasks, where the spectrum of possible answers was wider. We concluded that worksheets can be used effectively for acquiring basic knowledge about biodiversity and suggest how to integrate the findings into the design of worksheets for out-of-school learning.

Localization of a storage protein in the wood ray parenchyma cells of Taxodium distichum (L.) L. C. Rich. by immunogold labeling

SummaryUltrastructural investigations showed the occurrence of electron-dense intravacuolar aggregations in wood ray cells of Taxodium distichum (L.) L. C. Rich, during the dormant season. Such aggregations were missing in summer. By SDS-PAGE of the crude protein extract of Taxodium, a prominent protein of about 35 kDa was detected before budbreak. This protein disappeared at the time when the new shoots had fully grown out. An antibody was raised against this “storage protein”. In the immunoblot the antibody reacted specifically with the 35 kDa protein. At the electron-microscope level, by immunogold labeling, the electron-dense intravacuolar aggregations were identified as the specific storage sites for the 35 kDa protein. Thus, these vacuoles proved to be “protein storing vacuoles”.

Storage Proteins in the Wood of Taxodiaceae and of Taxus

Summary Using SDS-PAGE, a prominent polypeptide of ca. 35 kDa was found in the wood extract of Taxodium distichum . It disappeared during growth of new shoots in spring and accumulated again in fall, suggesting its significance in protein storage. Antibodies raised against this protein also showed strong immunochemical reaction with proteins of 32 and 34 kDa extracted from the wood of Metasequoia glyptostroboides . In contrast, the evergreen species Sequoiadendron giganteum did not give a positive immunological response at the fall stage investigated, while two polypeptide bands of about 34 and 36 kDa of Taxus were slightly but significantly positive against this anti-35 kDa protein antibody of Taxodium . The widespread occurrence of possibly closely related storage proteins thus is indicated.

Using doubly latent multilevel analysis to elucidate relationships between science teachers’ professional knowledge and students’ performance

ABSTRACT Teachers make a difference for the outcome of their students in science classrooms. One focus in this context lies on teachers’ professional knowledge. We describe this knowledge according to three domains, namely (1) content knowledge (CK), (2) pedagogical content knowledge (PCK), and (3) curricular knowledge (CuK). We hypothesise a positive relationship between these three domains and students’ performance in science. Students’ science performance was conceptualised by system thinking performance in the context of biology teaching. In order to test our hypothesis, we examined the relationship between the knowledge triplet CK, PCK, and CuK and students’ performance. 48 biology teachers and their students (N = 1036) participated in this study. Teachers’ content-related professional knowledge and students’ performance were measured by paper-and-pencil tests. Moreover, we used concept maps to further assess students’ performance. By specifying doubly latent models, we found a significant positive relationship between biology teachers’ PCK and students’ performance. On the contrary, the results reveal no relationship between CK and CuK and students’ performance. These findings are discussed in respect to modelling the interrelationship of teachers’ content-related professional knowledge and students’ learning in science, as well as concerning their relevance for further research and teacher education programmes.

Students’ arguments on the science and religion issue: the example of evolutionary theory and Genesis

Treating creationism as a controversial topic within the science and religion issue in the science classroom has been widely discussed in the recent literature. Some researchers have proposed that this topic is best addressed by focusing on sociocognitive conflict. To prepare new learning opportunities for this approach, it is necessary to know the concrete arguments that students use in their discussions on this issue. Therefore, this study aimed to provide a systematic description of these arguments. For this purpose, upper secondary students (N = 43) argued for either the acceptance of evolutionary theory or faith in Genesis in a written speech. The study was conducted during their regular biology and religious education classes. Generated arguments were analysed by qualitative content analysis. Three dimensions of the arguments were described: the content (science or religion), the valuation of the argument (positive or negative), and whether the argument consisted of a descriptive or normative argumentation. The results indicate that students found it easier to generate arguments about the scientific side of the issue; however, these arguments were negatively constructed. The results are discussed with regard to implications for educational approaches for teaching controversial issues at the high-school level.

Tackling the Difficulties in Learning Evolution: Effects of Adaptive Self-Explanation Prompts.

Abstract Teaching and learning evolution is challenging. Biology education research shows that the underlying evolutionary concepts are poorly understood among students. This prevents a meaningful understanding of the central biological concepts. The instructional format of self-explanation prompts seems to be promising to respond to these difficulties. However, previous research has shown that the interaction between prior knowledge and prompts is an important factor in enhancing effective self-explanations. Nevertheless, there are hardly any studies which focus on the majority of learners in the classrooms, ie students with average prior knowledge. The aim of this study was to analyse the requirements of adaptive self-explanation prompts specifically for these learners. This should enable students at all knowledge levels to be effectively fostered in self-explaining, while they are learning evolution. We investigated the effects of three kinds of prompts for fostering self-explanations: learners with average prior knowledge were prompted with low or/and high-knowledge prompts. Our analysis of 22 verbal protocols by middle-school German students shows that the prompts evoked the intended self-explanations. The most positive impact with regard to self-explanation quality was created by the prompting condition which combines low-knowledge and high-knowledge self-explanation characteristics.

Analysis of students’ arguments on evolutionary theory

A qualitative exploratory study was conducted to reveal students’ argumentation skills in the context of the topic of evolution. Transcripts from problem-centred interviews on secondary students’ beliefs about evolutionary processes of adaptation were analysed using a content analysis approach. For this purpose two categorical systems were deductively developed: one addressing the complexity of students’ arguments, the other focusing on students’ use of argumentation schemes. Subsequently, the categorical systems were inductively elaborated upon the basis of the analysed material showing a satisfactory inter-rater reliability. Regarding the arguments’ complexity, students produced mainly single claims or claims with a single justification consisting of either data or warrants. With regard to argumentation schemes students drew their arguments mainly using causal schemes, analogies, or illustrative examples. Results are discussed in light of possible implications for teaching evolutionary theory using classroom argumentation.

Biochemical and Immunological Investigations on Vegetative Storage Proteins of Taxodiaceae Species

Summary Vegetative storage proteins were investigated in the wood and bark of the Taxodiaceae Metasequoia, Sequoiadendron and Taxodium . In the wood of the deciduous Metasequoia glyptostroboides and the evergreen Sequoiadendron giganteum , prominent proteins were detected by SDS-PAGE during the dormant period, which showed strong seasonal fluctuations. The apparent molecular weights of these vegetative storage proteins are 34 kD and 32 kD in the wood of Metasequoia (SP-M34, SP-M32) and 32 kD and 30 kD in the wood of Sequoiadendron (SP-S32, SP-S30). A specific antibody raised against the 35 kD storage protein of Taxodium distichum wood (SP-T35) showed clearcut cross-reactions with SP-M34, SP-S32 and SP-S30. In the bark of the three Taxodiaceae species, prominent proteins corresponding in molecular weight to the respective wood storage proteins of these species were detected in January. These proteins clearly react with the SP-T35 antibody as well, indicating similarities between these wood and bark storage proteins. After peptide mapping with V8-protease from Staphylococcus aureus , SP-T35, SP-M34, SP-S32 and SP-S30 each show a degradation product of 19 kD in the protein pattern visible after SDS-PAGE. All the storage proteins detected are glycosylated. After enzymatic deglycosylation with N-glycosidase F, both SP-T35 and SP-M34 showed a 32 kD protein band. These 32 kD protein bands lack Con A binding although they still show a clearcut reaction with the antibody produced against SP-T35. This strongly suggests that the antibody reacts with the peptide moiety of the glycoproteins and not exclusively with the oligosaccharide chains. Analysis of the oligosaccharide chains of SP-T35 and SP-M34 by different lectins showed that «high mannose» as well as complex sugar chains are bound to the apoproteins. By immunogold labeling, the 34 kD protein of Metasequoia could be located in so-called protein storage vacuoles in the ray parenchyma cells of the wood.