Co-operative learning and adaptive instruction in a mathematics curriculum

The AGO 12 to 16 Project (the acronym AGO stands for the Dutch equivalent of 'Adaptive Instruction and Co-operative Learning') seeks to develop and evaluate a mathematics curriculum which is suitable for mixed-ability groups in secondary education. The research questions we will address here are, first, whether this curriculum is feasible and effective, and, second, what effects, if any, the context variables time and mean cognitive level of the class have on learning. Many mathematics programmes make insufficient allowance for the differences in intellectual ability that exist in mixed-ability classes. In order to change this situation we developed a mathematics curriculum with adaptive qualities. The evaluation of the experimental curriculum was carried out in two stages. During the first stage the curriculum was used at two schools with the aim of investigating the feasibility of the programme. Experience with the implementation of the programme led to some improvements in the experimental materials. By and large the AGO model appeared to be feasible in secondary classrooms. In the second stage, which was on a large scale, the focus was on the effectiveness of the programme. Six hundred students, 13 teachers and six schools were involved in the research. Teachers in the experimental group were trained in AGO methods and in implementing the new AGO curriculum. Teachers in the control groups worked with the existing programme following their usual methods of teaching. The main conclusion of the study is positive. The AGO model as a whole proved to be practical and effective in learning mathematics. The AGO model has a positive effect on the intercept, which means that the mean scores of AGO classes are higher than the mean scores of non-AGO classes. It may be concluded that, on the average, students benefit from learning in AGO classes as compared with non-AGO classes. AGO does not increase or decrease the differences between students in the same class. As expected, positive effects of two context variables were found: (1) the total amount of time spent in class covering the mathematical content and (2) class composition as indicated by the mean pretest score (aptitude) of the class

‘Ik dacht van: ik ga gewoon naar de middelbare school’. Over de betekenis van hulpbronnen in de schoolloopbaan van leerlingen

Dit artikel betreft een longitudinaal, overwegend kwalitatief onderzoek naar de schoolloopbaan van leerlingen. Het gehanteerde onderwijspedagogisch perspectief gaat uit van een visie op de taak van de school en op de hulpbronnen (resources) die bij de ontwikkeling van leerlingen een rol spelen. Uit een databestand van 239 basisschoolleerlingen op de leeftijd van tien jaar zijn drie casus-leerlingen gekozen. Deze leerlingen zijn na de basisschool op drie schooltypen terechtgekomen: vmbo, havo en vwo. Vervolgens zijn zij als jongvolwassenen uitgestroomd naar diverse situaties. Het onderzoeksdesign kan worden getypeerd als een embedded case study waarbij een methode van narrative inquiry wordt gehanteerd. Naast gegevens omtrent de cognitieve ontwikkeling zoals Cito-scores en andere toetsgegevens, zijn gegevens verzameld aan de hand van diepte-interviews met leerlingen, hun ouders en leraren. De leerlingen zijn in drie onderzoeksronden gevolgd gedurende de leeftijdsfase van 10 - 21 jaar. De vraagstelling is: Hoe verloopt de schoolloopbaan van leerlingen van 10-21 jaar, hoe wordt dit verloop door hen ervaren en wat is de betekenis van ‘resources’ in de ontwikkeling van deze leerlingen? Het artikel beschrijft vanuit het perspectief van de leerling hoe schoolloopbanen verlopen. Bij de analyse wordt ingegaan op de betekenis van resources in de schoolloopbaan. Het talent van een leerling - zoals dat tot uitdrukking komt in de prestaties op een reeks objectieve toetsen - lijkt doorslaggevend. Van motivatie en inzet kan een compenserende werking uitgaan. Gezondheid of ziekte speelt soms een cruciale rol in de schoolloopbaan. De betekenis van ouders en leraren wordt vooral zichtbaar op de breukvlakken in de schoolloopbaan. Summary In the last few decades considerable progress has been made in the empirical study of school careers. Somewhat surprisingly perhaps, students themselves have hardly had a voice in the majority of these large scale quantitative studies. This article is an attempt to redress the balance: not only will the students, their parents and their teachers receive a voice, they will also be given ‘a face’. We follow the students on their journeys through educational institutions from the ages of 10 to 21, presenting their learning results as measured by a range of objective tests and placing their stories in the light of a resource theory. Some of the students will be seen advancing smoothly from primary education to the tertiary sector, while others will be seen falling by the wayside. The following main questions will be addressed in the investigation: (1) How do the school careers of 10-to-21 year-old students develop? (2) How are these careers experienced by the students themselves? (3) What explanations can be given from a resource-theoretical perspective? We will describe and analyse in detail the school careers of five students in a longitudinal research framework characterisable as a longitudinal ‘embedded case study’. In the context of this design the stories of the students and their teachers will be the main focus. However, this statement of focus does not imply a simple description of the experiences and perspectives of the people concerned. Rather, in this work we endeavour to connect the students’ ‘small stories’ to the ‘grand stories’ of the theory of school careers. The main conclusion from this research is that talent - as measured by scores on a series of objective tests at the ages of ten and twelve years – is the most influential resource in later school success, but that strong motivation has a compensating effect. Real ‘survivors’ sometimes achieve their aim by overcoming great barriers. Parents and teachers also play a very important role in particular at the transition points

The merger of vertically offset quasi-geostrophic vortices

We examine the critical merging distance between two equal-volume, equal-potential-vorticity quasi-geostrophic vortices. We focus on how this distance depends on the vertical offset between the two vortices, each having a unit mean height-to-width aspect ratio. The vertical direction is special in the quasi-geostrophic model (used to capture the leading-order dynamical features of stably stratified and rapidly rotating geophysical flows) since vertical advection is absent. Nevertheless vortex merger may still occur by horizontal advection. In this paper, we first investigate the equilibrium states for the two vortices as a function of their vertical and horizontal separation. We examine their basic properties together with their linear stability. These findings are next compared to numerical simulations of the nonlinear evolution of two spheres of potential vorticity. Three different regimes of interaction are identified, depending on the vertical offset. For a small offset, the interaction differs little from the case when the two vortices are horizontally aligned. On the other hand, when the vertical offset is comparable to the mean vortex radius, strong interaction occurs for greater horizontal gaps than in the horizontally aligned case, and therefore at significantly greater full separation distances. This perhaps surprising result is consistent with the linear stability analysis and appears to be a consequence of the anisotropy of the quasi-geostrophic equations. Finally, for large vertical offsets, vortex merger results in the formation of a metastable tilted dumbbell vortex.Publisher PDFPeer reviewe

Selective loss of noradrenaline exacerbates early cognitive dysfunction and synaptic deficits in APP/PS1 mice.

Background: Degeneration of the locus coeruleus (LC), the major noradrenergic nucleus in the brain, occurs early and is ubiquitous in Alzheimer’s disease (AD). Experimental lesions to the LC exacerbate AD-like neuropathology and cognitive deficits in several transgenic mouse models of AD. Because the LC contains multiple neuromodulators known to affect amyloid toxicity and cognitive function, the specific role of noradrenaline (NA) in AD is not well understood. Methods: To determine the consequences of selective NA deficiency in an AD mouse model, we crossed dopamine -hydroxylase (DBH) knockout mice with amyloid precursor protein (APP)/presenilin-1 (PS1) mice overexpressing mutant APP and PS1. Dopamine -hydroxylase (/) mice are unable to synthesize NA but otherwise have normal LC neurons and co-transmitters. Spatial memory, hippocampal long-term potentiation, and synaptic protein levels were assessed. Results: The modest impairments in spatial memory and hippocampal long-term potentiation displayed by young APP/PS1 or DBH (/) single mutant mice were augmented in DBH (/)/APP/PS1 double mutant mice. Deficits were associated with reduced levels of total calcium/calmodulin-dependent protein kinase II and N-methyl-D-aspartate receptor 2A and increased N-methyl-D-aspartate receptor 2B levels and were independent of amyloid accumulation. Spatial memory performance was partly improved by treatment with the NA precursor drug L-threo-dihydroxyphenylserine. Conclusions: These results indicate that early LC degeneration and subsequentNAdeficiency inADmay contribute to cognitive deficits via altered levels of calcium/calmodulin-dependent protein kinase II and N-methyl-D-aspartate receptors and suggest that NA supplementation could be beneficial in early AD

S-nitroso-N-acetylpenicillamine and nitroprusside induce apoptosis in a neuronal cell line by the production of different reactive molecules.

CHP212 neuroblastoma cells were exposed to two different nitric oxide (NO) donors, S-nitroso-N-acetylpenicillamine and sodium nitroprusside. Apoptosis and necrosis were determined with flow cytometric analysis of annexin V binding and propodium iodide uptake. Both S-nitroso-N-acetylpenicillamine and sodium nitroprusside induced apoptosis, but with a different time dependency. Oxyhemoglobin (NO scavenger) attenuated the toxicity of S-nitroso-N-acetylpenicillamine, but had no effect on the toxicity of sodium nitroprusside. By contrast, deferoxamine (iron chelator) attenuated the toxicity of sodium nitroprusside, but had no effect on the toxicity of S-nitroso-N-acetylpenicillamine. Urate (ONOO- scavenger) did not influence the toxicity of either S-nitroso-N-acetylpenicillamine or sodium nitroprusside, but protected from SIN-1 (3-morpholinosydnonimine, ONOO- donor). It was shown that both dithiothreitol and ascorbic acid affected the toxicity of S-nitroso-N-acetylpenicillamine and sodium nitroprusside in opposite ways. In the presence of dithiothreitol, superoxide dismutase and catalase decreased the toxicity of sodium nitroprusside. In the presence of cells, but not in their absence, S-nitroso-N-acetylpenicillamine decomposed with a half-life of about 4 h as assessed by the production of nitrite and absorbance reduction at 335 nm. Sodium nitroprusside decomposed Very slowly in the presence of cells as assessed by the production of ferrocyanide. It can be concluded that (1) slow and sustained release of NO from S-nitroso-N-acetylpenicillamine at the cell surface causes apoptosis in CHP212 cells, probably without the involvement of ONOO-, (2) sodium nitroprusside causes apoptosis by the production of H2O2 and/or iron, rather than NO, and probably has to be taken up by the cell for decomposition