4,596 research outputs found
Open ended tasks and barriers to learning : teachers\u27 perspectives
Examines barriers to learning mathematics when using an open-ended task teaching strategy. Features of an open-ended task; Benefits of an open-ended task; Problems concerning multiplicity of responses and contexts in an open-ended task.<br /
A Calibrated Measurement of the Near-IR Continuum Sky Brightness Using Magellan/FIRE
We characterize the near-IR sky background from 308 observations with the
FIRE spectrograph at Magellan. A subset of 105 observations selected to
minimize lunar and thermal effects gives a continuous, median spectrum from
0.83 to 2.5 microns which we present in electronic form. The data are used to
characterize the broadband continuum emission between atmospheric OH features
and correlate its properties with observing conditions such as lunar angle and
time of night. We find that the moon contributes significantly to the
inter-line continuum in the Y and J bands whereas the observed H band continuum
is dominated by the blended Lorentzian wings of multiple OH line profiles even
at R=6000. Lunar effects may be mitigated in Y and J through careful scheduling
of observations, but the most ambitious near-IR programs will benefit from
allocation during dark observing time if those observations are not limited by
read noise. In Y and J our measured continuum exceeds space-based average
estimates of the Zodiacal light, but it is not readily identified with known
terrestrial foregrounds. If further measurements confirm such a fundamental
background, it would impact requirements for OH-suppressed instruments
operating in this regime.Comment: 25 pages, 11 figures, accepted to PAS
Planning and teaching mathematics lessons as a dynamic, interactive process
We are researching actions that teachers can take to improve mathematics learning for all students, with particular attention to specific groups of students who might experience difficulty. After identifying possible barriers to learning, we offered teachers mathematics lessons structured in a particular way. Teachers’ use of the model outlined in this paper seemed productive and their resulting planning and teaching proved to be dynamic and interactive. This paper uses excerpts from a conversation between two teachers to illustrate specific aspects of the model.<br /
The Water Poverty Index: an International Comparison
This paper reports on the construction of an International Water Poverty Index, part of the first phase of a research project into building a locally based version of the index. The purpose of the Water Poverty Index is to express an interdisciplinary measure which links household welfare with water availability and indicates the degree to which water scarcity impacts on human populations. Such an index makes it possible to rank countries and communities within countries taking into account both physical and socio-economic factors associated with water scarcity. This enables national and international organisations concerned with water provision and management to monitor both the resources available and the socio-economic factors which impact on access and use of those resources. This paper presents details of the methodology used and the results obtained for 140 countries covering measures of resources, access, capacity, use and environment.Indicators, water, environment, water poverty, income poverty
Near-Infrared InGaAs Detectors for Background-limited Imaging and Photometry
Originally designed for night-vision equipment, InGaAs detectors are
beginning to achieve background-limited performance in broadband imaging from
the ground. The lower cost of these detectors can enable multi-band
instruments, arrays of small telescopes, and large focal planes that would be
uneconomical with high-performance HgCdTe detectors. We developed a camera to
operate the FLIR AP1121 sensor using deep thermoelectric cooling and
up-the-ramp sampling to minimize noise. We measured a dark current of 163-
s pix, a read noise of 87- up-the-ramp, and a well depth of
80k-. Laboratory photometric testing achieved a stability of 230 ppm
hr, which would be required for detecting exoplanet transits. InGaAs
detectors are also applicable to other branches of near-infrared time-domain
astronomy, ranging from brown dwarf weather to gravitational wave follow-up.Comment: Submitted to Proc. SPIE, Astronomical Telescopes + Instrumentation
(2014
Session 5: Development, Neuroscience and Evolutionary Psychology
Proceedings of the Pittsburgh Workshop in History and Philosophy of Biology, Center for Philosophy of Science, University of Pittsburgh, March 23-24 2001 Session 5: Development, Neuroscience and Evolutionary Psycholog
Precision of a Low-Cost InGaAs Detector for Near Infrared Photometry
We have designed, constructed, and tested an InGaAs near-infrared camera to
explore whether low-cost detectors can make small (<1 m) telescopes capable of
precise (<1 mmag) infrared photometry of relatively bright targets. The camera
is constructed around the 640x512 pixel APS640C sensor built by FLIR
Electro-Optical Components. We designed custom analog-to-digital electronics
for maximum stability and minimum noise. The InGaAs dark current halves with
every 7 deg C of cooling, and we reduce it to 840 e-/s/pixel (with a
pixel-to-pixel variation of +/-200 e-/s/pixel) by cooling the array to -20 deg
C. Beyond this point, glow from the readout dominates. The single-sample read
noise of 149 e- is reduced to 54 e- through up-the-ramp sampling. Laboratory
testing with a star field generated by a lenslet array shows that 2-star
differential photometry is possible to a precision of 631 +/-205 ppm (0.68
mmag) hr^-0.5 at a flux of 2.4E4 e-/s. Employing three comparison stars and
de-correlating reference signals further improves the precision to 483 +/-161
ppm (0.52 mmag) hr^-0.5. Photometric observations of HD80606 and HD80607 (J=7.7
and 7.8) in the Y band shows that differential photometry to a precision of 415
ppm (0.45 mmag) hr^-0.5 is achieved with an effective telescope aperture of
0.25 m. Next-generation InGaAs detectors should indeed enable Poisson-limited
photometry of brighter dwarfs with particular advantage for late-M and L types.
In addition, one might acquire near-infrared photometry simultaneously with
optical photometry or radial velocity measurements to maximize the return of
exoplanet searches with small telescopes.Comment: Accepted to PAS
Exploring the relationship between task, teacher actions, and student learning
We are examining actions that teachers take to convert tasks into learning opportunities. In this paper, we contrast ways that three teachers convert the same task into lessons, and the way that their lessons reflect their intent. We found that the teachers did what they intended to do, that this was connected to their appreciation of the mathematics involved, and directly influenced the learning opportunities of the students. To the extent that the potential of the task was reduced, this seemed due to the lack of mathematical confidence in the case of two of the teachers
Recommended from our members
A global climatology of wind–wave interaction
Generally, ocean waves are thought to act as a drag on the surface
wind so that momentum is transferred downwards, from the atmosphere
into the waves. Recent observations have suggested that when long
wavelength waves, characteristic of remotely generated swell,
propagate faster than the surface wind momentum can also be
transferred upwards. This upward momentum transfer acts to accelerate
the near-surface wind, resulting in a low-level wave-driven wind
jet. Previous studies have suggested that the sign reversal of the
momentum flux is well predicted by the inverse wave age, the ratio of
the surface wind speed to the speed of the waves at the peak of the
spectrum. ECMWF ERA-40 data has been used here to calculate the global
distribution of the inverse wave age to determine whether there are
regions of the ocean that are usually in the wind-driven wave regime
and others that are generally in the wave-driven wind regime. The
wind-driven wave regime is found to occur most often in the
mid-latitude storm tracks where wind speeds are generally high. The
wave-driven wind regime is found to be prevalent in the tropics where
wind speeds are generally light and swell can propagate from storms at
higher latitudes. The inverse wave age is also a useful indicator of
the degree of coupling between the local wind and wave fields. The
climatologies presented emphasise the non-equilibrium that exists
between the local wind and wave fields and highlight the importance of
swell in the global oceans
Teaching Mathematics: Using research-informed strategies
AER 59 reviews research into aspects of mathematics teaching, focusing on issues relevant to Australian mathematics teachers, to those who support them, and also to those who make policy decisions about mathematics teaching. It was motivated by and draws on the proceedings of the well-attended and highly successful ACER Research Conference Teaching mathematics? Make it count: What research tells us about effective mathematics teaching and learning, held in Melbourne in August 2010.
Section 2 describes the goals of teaching mathematics and argues that a practical orientation should be the focus of mathematics teaching in the compulsory years, and outlines the contribution numeracy-based perspectives can make to schooling. Section 3 uses assessment data to evaluate how well those goals are being met in Australia and introduces the challenge of seeking equity of opportunity in mathematics teaching and learning. Section 4 expands on the importance, to individuals and society, of achieving the mathematics goals; and Section 5 discusses six research-based principles of mathematics teaching. Section 6 argues for the importance of well-chosen mathematical tasks in supporting student learning, and models tasks and particular teaching strategies. Sections 7 and 8 analyse research which provides insights into a key issue facing Australian mathematics teachers, that of finding ways to address the needs of heterogeneous groups of students. Section 9 describes and recommends particular emphases and strategies for education programs for both prospective and practising teachers.https://research.acer.edu.au/aer/1022/thumbnail.jp
- …