Search

Implementation of a problem-based mathematics curriculum, the "Interactive Mathematics Program" (IMP), at three high schools in California has been associated with more than just differences in student achievement. The outcomes that distinguished students who participated in the IMP program from students who followed a conventional algebra/geometry syllabus were the students' perceptions of the discipline of mathematics, of mathematical activity and the origins of mathematical ideas, of the mathematical nature of everyday activities, and of school mathematics and themselves as mathematicians. A coherent and consistent picture has emerged of the set of beliefs, perceptions and performances arising from such a program. Students who have participated in the IMP program appear to be more confident than their peers in conventional classes; to subscribe to a view of mathematics as having arisen to meet the needs of society, rather than as a set of arbitrary rules; to value communication in mathematics learning more highly than students in conventional classes; and to be more likely than their conventionally-taught peers to see a mathematical element in everyday activity. These outcomes occurred while the IMP students maintained performance levels on the mathematics portion of the SAT at or above those of their peers in conventional classes. If student achievement outcomes are comparable, the mathematics education community must decide whether it values these consequences of a problem-based curriculum. (Contains 1 figure and 8 tables.)

We investigate a new proxy for ENSO climate variability based on particle-size data from long-term, coastal sediment records preserved in a barrier estuary setting. Corresponding ~4-8 year periodicities identified from Wavelet analysis of particle-size data from Pescadero Marsh in Central Coast California and rainfall data from San Francisco reflect established ENSO periodicity, as further evidenced in the Multivariate ENSO Index (MEI), and thus confirms an important ENSO control on both precipitation and barrier regime variability. Despite the fact that barrier estuary mean particle size is influenced by coastal erosion, precipitation and streamflow, balanced against barrier morphology and volume, it is encouraging that considerable correspondence can also be observed in the time series of MEI, regional rainfall and site-based mean particle size over the period 1871-2008. This correspondence is, however, weakened after c.1970 by temporal variation in sedimentation rate and event-based deposition. These confounding effects are more likely when: (i) accommodation space may be a limiting factor; and (ii) particularly strong El Niños, e.g. 1982/1983 and 1997/1998, deposit discrete >cm-thick units during winter storms. The efficacy of the sediment record of climate variability appears not to be compromised by location within the back-barrier setting, but it is limited to those El Niños that lead to barrier breakdown. For wider application of this particle size index of ENSO variability, it is important to establish a well-resolved chronology and to sample the record at the appropriate interval to characterize deposition at a sub-annual scale. Further, the sample site must be selected to limit the influence of decreasing accommodation space through time (infilling) and event-based deposition. It is concluded that particle-size data from back-barrier sediment records have proven potential for preserving evidence of sub-decadal climate variability, allowing researchers to explore temporal and spatial patterns in phenomena such as ENSO. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Establishing the future trajectories of coastal wetlands, especially the nature of their disturbance, response and recovery regimes, is of critical importance for a wide range of stakeholders and environmental managers. Reconstructing meso-scale behaviour in coastal environments can serve to attune coastal resource management strategies to natural scales of system operations, thus fostering genuine sustainability. Sediments from Pescadero Marsh, a back-barrier coastal wetland in California, were analysed down-core for their particle size distribution in consecutive 2-mm sections. The particle size data reflect changing hydrodynamics in the back-barrier area driven by past variations in barrier coherence. When considered together, the down-core mean particle size trend and particle size distribution curve styles provide considerable insight into meso-scale system behaviour, revealing barrier/back-barrier disturbance–response–recovery regimes, regime shifts and the role of aperiodic high-energy events in disturbing these regimes. Over sub-annual and multi-annual time periods, the behaviour of the Pescadero system was consistently characterised by both dynamic response to disturbance and recovery through negative feedback. Furthermore, over the duration of the analysed core section, that is, 1200–2300 years, the system was determined to have adopted a series of static equilibrium states. The barrier estuary behaviour reconstructed from the Pescadero sediment record is indicative of innate environmental resilience. [ABSTRACT FROM AUTHOR]