113 research outputs found

    Design Problems for Secondary Students

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    Are there different kinds of design problems? According to Brown and Chandrasekaran (1989), Class 1 design problems are open-ended, non-routine creative activities where the goals are ill-structured, and there is no effective design plan specifying the sequence of actions to take in producing a design model. Class 2 problems use existing, well-developed design and decomposition plans (e.g. designing a new automobile). Class 3 designs are routine where design and decomposition plans are known as well as customary actions taken to deal with failures (e.g., writing a computer program). Jonassen (2011) argued that problems vary in terms of structuredness, complexity, and context. On the structuredness and complexity continua, design problems tend to be the most ill-structured and complex. Brown and Chandrasekaran suggest that design problems may vary along a continuum from well-structured to ill-structured, depending upon the context in which they are solved. In formal, school contexts, design problems are often more constrained, allowing many fewer degrees of freedom in their representations, processes, or solutions and are therefore more well-structured

    Effects of semantically structured hypertextual knowledge bases on user knowledge structures

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    Some hypertext researchers and designers believe that hypertext information structures should reflect the structures of human memory and that by empirically deriving and then mapping the semantic structure of information onto hypertext and explicitly illustrating that structure in the hypertext interface will result in greater changes in the knowledge structures of the users (Jonassen, 1990, 1991b; Lambiotte et al., 1989; McAleese, 1990; McDonald, Paap and McDonald, 1990). This chapter introduces techniques for ascertaining an expert’s knowledge structure and mapping it onto hypertext. It then reviews the results of an ongoing series of studies that test these ideas. The studies show that merely illustrating content structures in the interface is not sufficient for helping learners acquire that structure. Rather, it is the nature of the processing task and goals for learning whilst interacting with a hypertext that determines the effects of its use on learners’ knowledge structures

    Why Do We Fall? Using Experiences of Failure to Design Case Libraries

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    Instructional designers can support ill-structured problem solving through case libraries that detail domain-specific principles. In this design project, case libraries were employed in an undergraduate sales management course to contextualize knowledge and describe the ill-structured nature of how solutions are derived to solve authentic problems. Whereas many learning environments employ examples of model behavior (Jonassen, 2011), this instructional design was innovative in that the case libraries consisted of sales management failure experiences as the means to facilitate learning. The failure cases embedded within the learning environment engendered design tensions on multiple levels throughout the instructional design. Specifically, this article discusses the issues of engaging the subject matter expert (SME) to talk about failure cases and subsequent challenges to translate the experiences into meaningful learning resources for ill-structured problem solving. Other challenges included how to strategically design the learning environment so that the case library was available at the optimal time for the learners. The design case concludes with a reflection upon the process

    From classroom reality to virtual classroom: the role of teacher-created scripts in the development of classroom simulation technology

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    This paper describes a specific kind of teacher narrative (the teacher created script) to support the design of a classroom simulation to be used in pre-service teacher education. We intend to share our experiences in exploring and developing the kind of narrative text which can be developed from a large reservoir of ethnographically generated data collected from the teachers and classrooms we have closely observed and documented over the last two decades. In particular, we explore the role which these narratives play within the development of the kind of classroom simulation we have produced. Reflection has long been acknowledged as a useful process for teachers to engage with. Also, the notion of formalising such reflections through writing has been acknowledged as a way to share, refine and articulate teaching practice. As stated by Barth (2001:66) “…with written words come the innermost secrets of schools”. This prototype simulation allows the user to adopt the role of a Kindergarten teacher using a daily literacy teaching episode we refer to as “days of the week” and encourages the user to reflect upon the decisions they make about the organisation and implementation of this recurring teaching experience. The range of options that occur in this simulation stem from the teacher-created script we developed drawing from our own teaching experiences and classroom-based research to shape this virtual classroom

    Intuitive and Informal Knowledge in Preschoolers’ Development of Probabilistic Thinking

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    Preschoolers develop a wide range of mathematical informal knowledge and intuitive thinking before they enter formal, goal-oriented education. In their everyday activities young children get engaged with situations that enhance them to develop skills, concepts, strategies, representations, attitudes, constructs and operations concerning a wide range of mathematical notions. Recently there is scientific interest in linking children’s informal and formal knowledge in order to provide them with opportunities to avoid biases aiming at formulating, perceiving, reflecting on and exercising probabilistic notions. The current study investigates preschoolers’ (N=90) intuitive understanding of the likelihood of events in a probabilistic task with spinners. Participants, at the age of 4 to 6, are tested on their predictions of the most probable outcome prior to and after an instructive session of reasoning. The probabilistic task, based on constructivist principles, includes methodological alterations concerning the sample space and the themes of the stimuli. Educational implications are further discussed under the general point of view that in order to link informal to formal mathematical learning in preschool classroom, the subject content and the cognitive capacity of children are important to match

    Homo- and Heterosubtypic Low Pathogenic Avian Influenza Exposure on H5N1 Highly Pathogenic Avian Influenza Virus Infection in Wood Ducks (Aix sponsa)

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    Wild birds in the Orders Anseriformes and Charadriiformes are the natural reservoirs for avian influenza (AI) viruses. Although they are often infected with multiple AI viruses, the significance and extent of acquired immunity in these populations is not understood. Pre-existing immunity to AI virus has been shown to modulate the outcome of a highly pathogenic avian influenza (HPAI) virus infection in multiple domestic avian species, but few studies have addressed this effect in wild birds. In this study, the effect of pre-exposure to homosubtypic (homologous hemagglutinin) and heterosubtypic (heterologous hemagglutinin) low pathogenic avian influenza (LPAI) viruses on the outcome of a H5N1 HPAI virus infection in wood ducks (Aix sponsa) was evaluated. Pre-exposure of wood ducks to different LPAI viruses did not prevent infection with H5N1 HPAI virus, but did increase survival associated with H5N1 HPAI virus infection. The magnitude of this effect on the outcome of the H5N1 HPAI virus infection varied between different LPAI viruses, and was associated both with efficiency of LPAI viral replication in wood ducks and the development of a detectable humoral immune response. These observations suggest that in naturally occurring outbreaks of H5N1 HPAI, birds with pre-existing immunity to homologous hemagglutinin or neuraminidase subtypes of AI virus may either survive H5N1 HPAI virus infection or live longer than naïve birds and, consequently, could pose a greater risk for contributing to viral transmission and dissemination. The mechanisms responsible for this protection and/or the duration of this immunity remain unknown. The results of this study are important for surveillance efforts and help clarify epidemiological data from outbreaks of H5N1 HPAI virus in wild bird populations

    Primary Coenzyme Q Deficiency in Pdss2 Mutant Mice Causes Isolated Renal Disease

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    Coenzyme Q (CoQ) is an essential electron carrier in the respiratory chain whose deficiency has been implicated in a wide variety of human mitochondrial disease manifestations. Its multi-step biosynthesis involves production of polyisoprenoid diphosphate in a reaction that requires the enzymes be encoded by PDSS1 and PDSS2. Homozygous mutations in either of these genes, in humans, lead to severe neuromuscular disease, with nephrotic syndrome seen in PDSS2 deficiency. We now show that a presumed autoimmune kidney disease in mice with the missense Pdss2kd/kd genotype can be attributed to a mitochondrial CoQ biosynthetic defect. Levels of CoQ9 and CoQ10 in kidney homogenates from B6.Pdss2kd/kd mutants were significantly lower than those in B6 control mice. Disease manifestations originate specifically in glomerular podocytes, as renal disease is seen in Podocin/cre,Pdss2loxP/loxP knockout mice but not in conditional knockouts targeted to renal tubular epithelium, monocytes, or hepatocytes. Liver-conditional B6.Alb/cre,Pdss2loxP/loxP knockout mice have no overt disease despite demonstration that their livers have undetectable CoQ9 levels, impaired respiratory capacity, and significantly altered intermediary metabolism as evidenced by transcriptional profiling and amino acid quantitation. These data suggest that disease manifestations of CoQ deficiency relate to tissue-specific respiratory capacity thresholds, with glomerular podocytes displaying the greatest sensitivity to Pdss2 impairment

    The Evolutionary Genetics and Emergence of Avian Influenza Viruses in Wild Birds

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    We surveyed the genetic diversity among avian influenza virus (AIV) in wild birds, comprising 167 complete viral genomes from 14 bird species sampled in four locations across the United States. These isolates represented 29 type A influenza virus hemagglutinin (HA) and neuraminidase (NA) subtype combinations, with up to 26% of isolates showing evidence of mixed subtype infection. Through a phylogenetic analysis of the largest data set of AIV genomes compiled to date, we were able to document a remarkably high rate of genome reassortment, with no clear pattern of gene segment association and occasional inter-hemisphere gene segment migration and reassortment. From this, we propose that AIV in wild birds forms transient “genome constellations,” continually reshuffled by reassortment, in contrast to the spread of a limited number of stable genome constellations that characterizes the evolution of mammalian-adapted influenza A viruses
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