Ellen M. Granger

The efficacy of student-centered instruction in supporting science learning

Puzzling Through Gravity Much of the excitement of scientific discovery seems to get lost when science is taught as facts by lectures. Granger et al. (p. 105) present a large study of outcomes comparing inquiry-based teaching with more traditional teaching methods. Over 2000 students were involved, in 125 classrooms of 4th- and 5th-graders. The classes studied space-science with a curriculum that uses models and evidence to entice students into improving their own understanding of the science. Students who were encouraged to use evidence to support their models seemed to develop improved knowledge of content. A randomized trial reveals that opportunities to support models with evidence aids understanding in grade-school students. Transforming science learning through student-centered instruction that engages students in a variety of scientific practices is central to national science-teaching reform efforts. Our study employed a large-scale, randomized-cluster experimental design to compare the effects of student-centered and teacher-centered approaches on elementary school students’ understanding of space-science concepts. Data included measures of student characteristics and learning and teacher characteristics and fidelity to the instructional approach. Results reveal that learning outcomes were higher for students enrolled in classrooms engaging in scientific practices through a student-centered approach; two moderators were identified. A statistical search for potential causal mechanisms for the observed outcomes uncovered two potential mediators: students’ understanding of models and evidence and the self-efficacy of teachers.

Role of acoustic striae in hearing: Mechanism for enhancement of sound detection in cats

We report the results of behavioral studies in cats conducted first, to demonstrate the presence of a monaural mechanism for the enhancement of signal to noise; and then to examine the necessity or sufficiency of the acoustic striae for this mechanism. The results show that cats do indeed have a monaural mechanism for enhancing the detection of tones in co-located background noise for noise levels at least as high as 60 dB SPL. The ablation-behavior results show that surgical section of the dorsal (DAS) and most of the intermediate (IAS) striae has no measurable effect on this mechanism. In sharp contrast, even partial section of the trapezoid body results in a profound and permanent deficit and this deficit is not accounted for by hearing loss alone. It is concluded that the ascending and descending fibers in the dorsal and intermediate acoustic striae are neither necessary nor sufficient for enhancing the detection of salient sounds in a noisy environment while the ascending or descending fibers in the ventral acoustic stria are sufficient and probably necessary.

Psychoacoustical contribution of each lateral lemniscus

Although each lateral lemniscus is required for sound localization in its contralateral hemifield, no auditory function is yet known for the neural activity evoked in the lemniscus ipsilateral to a sound source. In an attempt to assess the role played by the ipsilateral lemniscus, monaural cats were tested on an array of psychoacoustical tasks before and after surgical section of one or the other lateral lemniscus. The results show that the lemniscus contralateral to the remaining intact ear is either necessary or sufficient for 24 of the 26 tests administered. However, the lemniscus ipsilateral to the intact ear is both necessary and sufficient (or alternatively, the contralateral lemniscus makes no obvious contribution) to normal thresholds in two of the tasks: detection of low-frequency tones (< 4 kHz) and detection of low-frequency AM modulation. Because of their projections to the ipsilateral inferior colliculus via the ipsilateral lemniscus, the anatomical substrate of these two unusual tasks is probably the fibers from the MSO and possibly, the LSO, ipsilateral to the intact ear.

Essential Aspects of Science Teacher Professional Development

Current reform efforts in science place a premium on student sense making and participation in the practices of science. Given the disparity between these activities and current teaching practices, effective means of professional development around such practices must be identified. We use a close examination of 106 science teachers participating in Research Experiences for Teachers (RET) to identify, through structural equation modeling, the essential features in supporting teacher learning from these experiences. Findings suggest that participation in RET shape science teacher practice and beliefs, which in turn influence practice. Essential features of RET include engaging teachers socially in the research context and in research projects that are personally relevant to them. The model suggests ways to maximize the professional development potential of RET intended to support engagement in disciplinary practices.