This study focused on the conceptual understandings held by 78 preservice elementary teachers about moon phases, before and after instruction. Participants in the physics groups received instruction on moon phases in an inquiry‐based physics course; participants in the methods group received no instruction on moon phases. The instructive effect of two different types of preinstruction interviews also was compared. The instruction on moon phases used in the study is from Physics by Inquiry by Lillian McDermott. In the study, the method of inquiry followed a qualitative design, involving classroom observations, document analysis, and structured interviews. Inductive data analysis identified patterns and themes in the participants' conceptual understanding. Results indicate that without the instruction, most preservice teachers were likely to hold alternative conceptions on the cause of moon phases. Participants who had the instruction were much more likely to hold a scientific understanding after instruction. The instruction appears to be more effective in promoting a scientific understanding of moon phases than instruction previously reported in the literature. It also appears that using a three‐dimensional model or making two‐dimensional drawings during the preinstruction interviews does not have instructive value. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 633–658, 2002

Fourth-grade students' knowledge of observable moon phases and patterns of change, as well as conceptual understanding of the cause of moon phases, was investigated before and after special instruction. Pretest and post-test data for 48 students were used to address the research question related to observable moon phases and patterns of change. Interviews were conducted with 10 students on a post-only basis to provide data on understanding the cause of moon phases. The researchers used the constant comparative method to analyse data. Pretest results indicate these students had not met the expectations expressed in the U.S. Science Education Standards for lunar concepts. Post-test results reveal a very positive performance on observable moon phases and patterns of change, as well as the cause of moon phases. Interpretation and implications of these findings are provided.

This research consists of a longitudinal study of 12 female elementary preservice teachers' conceptual understanding over the course of several months. The context in which the participants received instruction was in an inquiry-based physics course, and the targeted science content was the cause of moon phases. Qualitative research methods, including observations and interviews, were used to investigate and describe participants' conceptual understanding over time. Participants were interviewed on their understanding of the cause of moon phases before instruction, 3 weeks after instruction, and again in delayed post-interviews several months after instruction. Patterns and themes in the participants' conceptual understanding were identified through constant-comparative data analysis. Consistent with results reported earlier, participants who had instruction that included recording and analyzing moon observations over time and psychomotor modeling of changes in moon phases were very likely to hold a scientific conceptual understanding shortly after instruction. The present study indicates a majority of participants continued to hold a scientific understanding six months or more after instruction. However, some participants reverted to alternative conceptions they had shown during the pre-interview. These results are interpreted utilizing contemporary conceptual change theory. ß

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This study investigated the effect of non-traditional guided inquiry instruction on middle school students' conceptual understandings of lunar concepts. Multiple data sources were used to describe participants' conceptions of lunar phases and their cause, including drawings, interviews, and a lunar shapes card sort. The data were analyzed via a constant comparative method to produce profiles of each participant's conceptual understandings and nonparametric tests also were used. Results revealed very positive performance for observable moon phases and patterns of change, as well as the cause of moon phases. Results indicated that significantly more participants shifted from drawing nonscientific shapes on the pretest to drawing scientific shapes on the post-test. Results for the drawings of moon phase sequences were similar in that significantly more participants shifted from drawing alternative waxing and waning sequences on the pretest to drawing scientific sequences on the post-test. Also, significantly more participants shifted from alternative understanding of the cause of the moon phases on the pretest to scientific understanding on the post-test. Implications of these findings and recommendations for further research are provided.

Results on studies of tunneling and conduction phenomena in thin metal-iron-oxide-metal sandwiches at helium temperature are described in this paper. Characteristic I-V curves have been studied for both dc and ac applied voltage signals. The main features of interest are a voltage breakdown observed above certain critical currents, and a large negative-resistance region observed on the decreasmg current leg of the I-V curve. The breakdown phenomenon exhibits a delay time that is a function of the overvoltage applied to the junction, and comparison with nucleation theory has suggested that some type of phase transition is occurring. We suggest a model based on the order-disorder transition that is known to occur in magnetic iron oxide, Fe 3 0 4 . We also discuss possible field ionization processes that could be playing a role in the transition. The sandwiches have been successfully utilized as amplifiers, and can also be set into self-oscillation under certain conditions. Examples of these features are included in the paper. The transition from high to low resistance observed in these sandwiches is similar to those observed in glassy semiconductors at higher temperatures, and certain comparisons may be useful in trying to understand the glassy-semiconductor behavior.

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Results on tunnel current flow in junctions using ferromagnetic metals as electrodes or as added impurities at the barrier electrode interface are reported in this paper. Oxides of the ferromagnetic metal and aluminum oxide have been used to form the insulating barrier in combination with a second electrode made from aluminum, silver, or iron. Complete data are reported for various types of junctions using iron and iron oxide and covering a zero-bias resistance range at 4.2°K from 10" 1 SI to above 10 8 ft. Preliminary results on junctions using cobalt and nickel are also reported. The most general feature of interest is a very strong non-Ohmic behavior at low bias voltage and a very rapid temperature dependence of tunnel conductance, particularly in the helium temperature range. Data obtained on AI-AI2O3-AI junctions doped with iron impurities at the AI2O3-AI interface show a strong zero-bias anomaly corresponding to a resistance maximum. This behavior appears to be generally explained by an anomalous scattering mechanism near zero bias and has been compared to the behavior of identical undoped A1-A1 2 0 3 -A1 junctions. The experiments on junctions using iron oxide barriers also show strong zero-bias anomalies, but in addition show a more complex temperature dependence and an unusual breakdown effect at high voltages. These latter features are possibly associated with special properties of magnetic iron oxide Fe 3 0 4 . The data on junctions with iron oxide barriers have also been compared to the behavior predicted by standard tunnel theory, and areas of qualitative agreement can be found if a relatively low barrier height is assumed. The appropriate barrier height has been estimated as 0.025 eV from Fowler-Nordheim plots of the data. The preliminary data on junctions made with CoO* and NiOs barriers also show some similar effects, but they are generally of smaller magnitude. The experimental data will be presented in detail along with a summary of the relevant theories. 2The symmetry of wave functions in the one-electron band theory of ferromagnetic solids is discussed. The exchange interaction, spin-orbit coupling, and coupling of spins to the magnetic induction vector B are included in the Hamiltonian. The resulting symmetry, which is not invariant under time reversal, can contain only those point operations which belong to the paramagnetic space group and leave the pseudovector B invariant at the same time. Character tables are presented for the case of face-centered cubic, body-centered cubic, and hexagonal close-packed structures and for various directions of B. Compatibility relations and lifting of degeneracies are discussed.