Assessing proxies of knowledge and difficultywith rubric-based instruments

The fields of psychometrics, economic education, and education have developed statistically-valid methods of assessing knowledge and learning. These methods include item response theory, value-added learning models, and disaggregated learning. These methods, however, focus on multiple-choice or single response assessments. Faculty and administrators routinely assess knowledge through papers, thesis presentations, or other demonstrations of knowledge assessed with rubric rows. This paper presents a statistical approach to estimating a proxy for student ability and rubric row difficulty. Moreover, we have developed software so that practitioners can more easily apply this method to their instruments. This approach can be used in researching education treatment effects, practitioners measuring learning outcomes in their own classrooms, or estimating knowledge for administrative assessment. As an example, we have applied these new methods to projects in a large Labor Economics course at a public university

Create random assignments: A cloud-based tool to help implement alternative teaching materials

Research has shown that learning is enhanced by variety (Bransford, Brown, and Cocking 2000; Halpern and Hakel 2003) such as popular press books, podcasts and videos. However, these mediums do not contain question banks and further, while learning management systems (LMS) can be used to generate random quizzes, they are not designed for long-form open-ended responses that might be answered over the course of a few days to weeks; open-ended questions are often ideal in upper-level undergraduate and MBA courses where there are less definitive correct answers. We solve these problems by developing software to generate assignments with randomized open-ended questions

Lesson Plans for Teaching Economics with The Big Bang Theory

Using examples in the classroom from current and past television shows and movies is becoming increasingly common. Being able to relate ideas back to a popular clip or episode allows the instructor to reach students in ways the traditional lecture cannot. Building on the work of Tierney, Mateer, Smith, Wooten, and Geerling (2016), this paper introduces five lesson plans tied to clips from The Big Bang Theory that can be used in high school (9-12) economics courses

Approximate ab initio calculation of vibrational properties of hydrogenated amorphous silicon with inner voids

We have performed an approximate ab initio calculation of vibrational properties of hydrogenated amorphous silicon (a-Si:H) using a molecular dynamics method. A 216 atom model for pure amorphous silicon (a-Si) has been employed as a starting point for our a-Si:H models with voids that were made by removing a cluster of silicon atoms out of the bulk and terminating the resulting dangling bonds with hydrogens. Our calculation shows that the presence of voids leads to localized low energy (30-50 cm^{-1}) states in the vibrational spectrum of the system. The nature and localization properties of these states are analyzed by various visualization techniques.Comment: 15 pages with 6 PS figures, to appear in PRB in December 199

Improving Student Performance Through Loss Aversion

Framing an outcome as a loss causes individuals to expend extra effort to avoid that outcome (Tversky & Kahneman, 1991). Since classroom performance is a function of student effort in search of a higher grade, we seek to use loss aversion to encourage student effort. This field quasi-experiment endows students with all of the points in the course upfront, then deducts points for each error throughout the semester. Exploiting two course sequences in the business school of a Midwestern university, a control for domain-specific knowledge, this study examines the impact of loss aversion when controlling for the student’s knowledge in a specific subject. This quasi-experiment indicates that students perform three to four percentage points better when controlling for student ability and domain knowledge (148 subjects). This result is significant at the 1% level in our most robust specification (p = 0.0020). This result is confirmed by a specification including four courses and controlling for student characteristics (217 subjects, p = 0.0190)

Structure and energetics of the Si-SiO_2 interface

Silicon has long been synonymous with semiconductor technology. This unique role is due largely to the remarkable properties of the Si-SiO_2 interface, especially the (001)-oriented interface used in most devices. Although Si is crystalline and the oxide is amorphous, the interface is essentially perfect, with an extremely low density of dangling bonds or other electrically active defects. With the continual decrease of device size, the nanoscale structure of the silicon/oxide interface becomes more and more important. Yet despite its essential role, the atomic structure of this interface is still unclear. Using a novel Monte Carlo approach, we identify low-energy structures for the interface. The optimal structure found consists of Si-O-Si "bridges" ordered in a stripe pattern, with very low energy. This structure explains several puzzling experimental observations.Comment: LaTex file with 4 figures in GIF forma

Inclusion of Experimental Information in First Principles Modeling of Materials

We propose a novel approach to model amorphous materials using a first principles density functional method while simultaneously enforcing agreement with selected experimental data. We illustrate our method with applications to amorphous silicon and glassy GeSe$_2$. The structural, vibrational and electronic properties of the models are found to be in agreement with experimental results. The method is general and can be extended to other complex materials.Comment: 11 pages, 8 PostScript figures, submitted to J. Phys.: Condens. Matter in honor of Mike Thorpe's 60th birthda

Terahertz Conductivity at the Verwey Transition in Magnetite

The complex conductivity at the (Verwey) metal-insulator transition in Fe_3O_4 has been investigated at THz and infrared frequencies. In the insulating state, both the dynamic conductivity and the dielectric constant reveal a power-law frequency dependence, the characteristic feature of hopping conduction of localized charge carriers. The hopping process is limited to low frequencies only, and a cutoff frequency nu_1 ~ 8 meV must be introduced for a self-consistent description. On heating through the Verwey transition the low-frequency dielectric constant abruptly decreases and becomes negative. Together with the conductivity spectra this indicates a formation of a narrow Drude-peak with a characteristic scattering rate of about 5 meV containing only a small fraction of the available charge carriers. The spectra can be explained assuming the transformation of the spectral weight from the hopping process to the free-carrier conductivity. These results support an interpretation of Verwey transition in magnetite as an insulator-semiconductor transition with structure-induced changes in activation energy.Comment: 6 Pages, 3 Figure

Reverse Monte Carlo modeling of amorphous silicon

An implementation of the Reverse Monte Carlo algorithm is presented for the study of amorphous tetrahedral semiconductors. By taking into account a number of constraints that describe the tetrahedral bonding geometry along with the radial distribution function, we construct a model of amorphous silicon using the reverse monte carlo technique. Starting from a completely random configuration, we generate a model of amorphous silicon containing 500 atoms closely reproducing the experimental static structure factor and bond angle distribution and in improved agreement with electronic properties. Comparison is made to existing Reverse Monte Carlo models, and the importance of suitable constraints beside experimental data is stressed.Comment: 6 pages, 4 PostScript figure

Optical investigation on the electronic structures of Y_{2}Ru_{2}O_{7}, CaRuO_{3}, SrRuO_{3}, and Bi_{2}Ru_{2}O_{7}

We investigated the electronic structures of the bandwidth-controlled ruthenates, Y$_{2}$Ru$_{2}$O$_{7}$, CaRuO$_{3}$, SrRuO$_{3}$, and Bi$_{2}$Ru$_{2}$O$_{7}$, by optical conductivity analysis in a wide energy region of 5 meV $\sim$ 12 eV. We could assign optical transitions from the systematic changes of the spectra and by comparison with the O 1$s$ x-ray absorption data. We estimated some physical parameters, such as the on-site Coulomb repulsion energy and the crystal-field splitting energy. These parameters show that the 4$d$ orbitals should be more extended than 3$d$ ones. These results are also discussed in terms of the Mott-Hubbard model.Comment: 12 pages (1 table), 3 figure