Alexander Ruf

Towards a conceptualization of pedagogical content knowledge for computer science

ccording to the current state of research, it seems uncontroversial that the Pedagogical Content Knowledge (PCK) of teachers is a crucial factor for the success of teaching and learning in the context of many school subjects. Yet, the research about PCK in the subject of computer science (CS) is still sparse. Thus, we are working on a conceptualization of PCK for computer science (CS) that is based on literature on the one hand and empirically validated on the other. As a first step towards this goal, we have developed a category system from a set of publications from general pedagogy as well as from educational research in other subjects. Additionally, we have compared this system with the outcomes of a former survey among teachers about the preparation of lessons. Currently, we are coding all curricula for teacher education in Germany with this category system and preparing interviews among experts, applying the Critical Incident Technique.

Previously unknown class of metalorganic compounds revealed in meteorites

Significance In this study we report the discovery of a previously unrecognized chemical class, dihydroxymagnesium carboxylates, [(HO)2MgO2CR]−, gained from nonterrestrial meteoritic analyses. The existence of such low-coordination organomagnesium anionic compounds expands our knowledge and understanding of extreme environments from which the early solar system emerged and has evolved. The appearance this CHOMg chemical class extends the previously investigated vast diversity of CHNOS groups in meteoritic soluble organics. Experimental evidence is given for the connection between the evolution of organic compounds and minerals. These thermostable compounds might have contributed to the stabilization of organic molecules on a geological time scale, which emphasizes their potential astrobiological relevance. The rich diversity and complexity of organic matter found in meteorites is rapidly expanding our knowledge and understanding of extreme environments from which the early solar system emerged and evolved. Here, we report the discovery of a hitherto unknown chemical class, dihydroxymagnesium carboxylates [(OH)2MgO2CR]−, in meteoritic soluble organic matter. High collision energies, which are required for fragmentation, suggest substantial thermal stability of these Mg-metalorganics (CHOMg compounds). This was corroborated by their higher abundance in thermally processed meteorites. CHOMg compounds were found to be present in a set of 61 meteorites of diverse petrological classes. The appearance of this CHOMg chemical class extends the previously investigated, diverse set of CHNOS molecules. A connection between the evolution of organic compounds and minerals is made, as Mg released from minerals gets trapped into organic compounds. These CHOMg metalorganic compounds and their relation to thermal processing in meteorites might shed new light on our understanding of carbon speciation at a molecular level in meteorite parent bodies.

Classification of Programming Tasks According to Required Skills and Knowledge Representation

Tasks represent a central part of computer science lessons, and aim to practice programming skills or to concrete abstract concepts for example. We have investigated, which types of tasks are given to novice programmers, typically. For that purpose, we have analyzed and generalized tasks from textbooks and exercise sheets. The result is a list of twelve task types classified according to required skills and knowledge representation. In addition, we found that the task types differ very much regarding their incidence. Finally, we tried to relate the three found forms of knowledge representation to concepts of cognitive psychology.

Towards a Competency Model for Object-Oriented Programming

The German educational system is shifting towards the competences of learners since the publication of the national results of the OECD PISA studies with the goals to improve the overall learning outcomes, better individualize learning and teaching processes and also to promote the comparability of federal educational systems. Many disciplines have already developed empirically founded competency models and associated instruments to measure, compare, and interpret learner performance. Computer science education research is still in its infancy in this regard. It is therefore the aim of this project to develop such a model for the basics of object-oriented programming.

Types of assignments for novice programmers

This paper deals with the classification of assignments according to their type. In contrast to other publications, we derive assignment types not deductively, but extract them empirically from different sources. Our main research question is: What types of programming assignments are actually given to novice programmers? In addition, we compare our empirically found assignment types to the deductively derived ones from the literature. This is driven by the following research questions: Are there types of assignments that are mentioned in literature, which however are not or rarely found in actual assignments given to novice programmers? Can assignment types be found that cannot or only poorly be matched with the category types described in the literature?

Data-Driven Astrochemistry: One Step Further within the Origin of Life Puzzle

Astrochemistry, meteoritics and chemical analytics represent a manifold scientific field, including various disciplines. In this review, clarifications on astrochemistry, comet chemistry, laboratory astrophysics and meteoritic research with respect to organic and metalorganic chemistry will be given. The seemingly large number of observed astrochemical molecules necessarily requires explanations on molecular complexity and chemical evolution, which will be discussed. Special emphasis should be placed on data-driven analytical methods including ultrahigh-resolving instruments and their interplay with quantum chemical computations. These methods enable remarkable insights into the complex chemical spaces that exist in meteorites and maximize the level of information on the huge astrochemical molecular diversity. In addition, they allow one to study even yet undescribed chemistry as the one involving organomagnesium compounds in meteorites. Both targeted and non-targeted analytical strategies will be explained and may touch upon epistemological problems. In addition, implications of (metal)organic matter toward prebiotic chemistry leading to the emergence of life will be discussed. The precise description of astrochemical organic and metalorganic matter as seeds for life and their interactions within various astrophysical environments may appear essential to further study questions regarding the emergence of life on a most fundamental level that is within the molecular world and its self-organization properties.