Entwicklung eines Instruments zur Erfassung des Operationsverständnisses der Multiplikation

Obwohl Operationsverständnis mit der Rechenleistung in einem Zusammenhang zu stehen scheint (Ladel, 2011; Moser Opitz, 2005, 2007; Radatz, 1989; Royar, 2011, 2013; Schäfer, 2005) beziehungsweise ein unzureichendes Operationsverständnis zu den Hauptmerkmalen von Rechenschwierigkeiten gehört (Gerster & Schultz 2005; Moser Opitz, 2001; Schäfer, 2005; Schipper, 2005), liegen nur wenige empirische Untersuchungen zum Operationsverständnis vor. Um Operationsverständnis und seine Determinanten systematisch untersuchen zu können, ist ein Instrument erforderlich, mit dem Operationsverständnis zuverlässig erfasst werden kann. Die Entwicklung eines solchen Instrumentes wird im vorliegenden Beitrag erläutert

Impacts of climate change on plant diseases – opinions and trends

There has been a remarkable scientific output on the topic of how climate change is likely to affect plant diseases in the coming decades. This review addresses the need for review of this burgeoning literature by summarizing opinions of previous reviews and trends in recent studies on the impacts of climate change on plant health. Sudden Oak Death is used as an introductory case study: Californian forests could become even more susceptible to this emerging plant disease, if spring precipitations will be accompanied by warmer temperatures, although climate shifts may also affect the current synchronicity between host cambium activity and pathogen colonization rate. A summary of observed and predicted climate changes, as well as of direct effects of climate change on pathosystems, is provided. Prediction and management of climate change effects on plant health are complicated by indirect effects and the interactions with global change drivers. Uncertainty in models of plant disease development under climate change calls for a diversity of management strategies, from more participatory approaches to interdisciplinary science. Involvement of stakeholders and scientists from outside plant pathology shows the importance of trade-offs, for example in the land-sharing vs. sparing debate. Further research is needed on climate change and plant health in mountain, boreal, Mediterranean and tropical regions, with multiple climate change factors and scenarios (including our responses to it, e.g. the assisted migration of plants), in relation to endophytes, viruses and mycorrhiza, using long-term and large-scale datasets and considering various plant disease control methods

The Relationship between Flexible and Self-Regulated Learning in Open and Distance Universities

Flexibility in learning provides a student room for volitional control and an array of strategies and encourages persistence in the face of difficulties. Autonomy in and control over one’s learning process can be seen as a condition for self-regulated learning. There are a number of categories and dimensions for flexible learning; following professional publications, time, location, lesson content, pedagogy method, learning style, organization, and course requirements are all elements to consider. Using these categories and the dimensions of flexible learning, we developed and validated a questionnaire for an open and distance learning setting. This article reports on the results from a study investigating the relationship between flexible learning and self-regulated learning strategies. The results show the positive effects of flexible learning and its three factors, time management, teacher contact, and content, on self-regulated learning strategies (cognitive, metacognitive, and resource-based). Groups that have high flexibility in learning indicate that they use more learning strategies than groups with low flexibility

Nematode functional guilds, not trophic groups, reflect shifts in soil food webs and processes in response to interacting global change factors

Soils store ~80% of global terrestrial organic carbon and alterations in fluxes into and out of this pool may interact with ongoing climate change. Belowground food webs drive soil C dynamics, but little is known about their responses to co-occurring global change agents. We investigated open-air experimental grassland communities at ambient and elevated atmospheric CO2 concentration, ambient and enriched nitrogen input, and ambient and reduced summer precipitation to evaluate how these agents interactively affect soil nematodes, which are often used as an indicator group for soil food web structure and soil health. The aim of the study was to elucidate the response of the functional diversity of soil nematodes to changing environmental conditions by using nematode functional guilds and indices as indicators.The results suggest that nematode functional guilds surpass nematode trophic groups as soil indicators, suggesting that more detailed data on nematode community structure is essential to capture functional changes in response to environmental change. For instance, the density of opportunistic fungal feeders increased due to N addition with the response being more pronounced at elevated CO2, whereas densities of sensitive fungal-feeders were increased at ambient N and elevated CO2, illustrating opposing responses within one trophic group. Opportunistic bacterial feeders increased at elevated N, but did not respond to other environmental factors studied. Root-feeding Longidoridae were significantly reduced at elevated CO2 and elevated N compared to ambient conditions, whereas other plant feeders were little affected by the manipulations. Predacious nematodes were less abundant at elevated N, and the Structure Index (which indicates food web structure) suggested reduced top-down forces and simplified soil food webs, although omnivores did not vary significantly. Elevated CO2 buffered the effect of reduced precipitation on the Enrichment Index (which indicates increased resource availability) and the Channel Index (which indicates changes in decomposition channel) probably due to reduced stomatal conductance at elevated CO2. Further, the results suggest that the decomposer community switched from a bacterial-dominated to a fungal-dominated system at elevated N, indicating shifts in the microbial community as well as in the functioning of belowground food webs. Overall, the studied global change agents interactively and differentially affected functional guilds of soil nematodes, suggesting complex changes in soil processes. We highlight that detailed information on the functional guilds of nematodes is likely necessary to fully understand alterations in soil food webs and related processes due to global environmental change