Video-enhanced or textual rubrics: Does the Viewbrics' formative assessment methodology support the mastery of complex (21st century) skills?

Learners in the process of developing complex skills need a rich mental model of what such skills entail. Textual analytics rubrics (TR) are a widely used instrument to support formative assessment of complex skills, supporting feedback, reflection, and thus mental model development of complex skills. However, the textual nature of a rubric limits the possibility to deliver contextual and dynamic (time-and behaviour-oriented) information. In the Viewbrics online tool, we developed a version supporting the delivery of contextual and dynamic information by adding video-modelling examples with embedded self-explanation prompts to textual analytics rubrics. We called this combination as video-enhanced rubrics (VERs). Our current study investigates whether the Viewbrics online tool supports complex skills development and whether either textual- or video-enhanced rubrics best support complex skills' mastery. The study was a three-group (VERS n = 49, TR n = 54, control n = 50) within-subjects design. Learners' performance of complex skills was measured through expert, peer, and self-assessment using the Viewbrics online tool. A multilevel regression analysis shows learners in the TR and VERS conditions consistently outperforming the control condition to varying degrees across skills. However, no differences have been found between the two experimental conditions. Positive results across different complex skills indicate the Viewbrics online tool can be used to support the development of a wide range of complex skills in secondary education.Web Information System

Charge Carrier Dynamics upon Sub-bandgap Excitation in Methylammonium Lead Iodide Thin Films: Effects of Urbach Tail, Deep Defects, and Two-Photon Absorption

To further understand the optoelectronic properties of metal halide perovskites, we investigate sub-bandgap absorption in methylammonium lead iodide (MAPbI3) films. Charge carrier dynamics are studied using time-resolved microwave conductivity measurements using sub-bandgap excitation. From changes in the decay dynamics as a function of excitation energy and intensity, we have identified three regimes: (i) Band-like charge transport at photon energies above 1.48 eV; (ii) a transitional regime between 1.48 and 1.40 eV; and (iii) below 1.40 eV localized optically active defects (8 × 1013 cm-3) dominate the absorption at low intensities, while two-photon absorption is observed at high intensities. We determined an Urbach energy of approximately 11.3 meV, indicative of a low structural and/or thermal disorder. Surprisingly, even excitation 120 meV below the bandgap leads to efficient charge transfer into electron (C60) or hole (spiro-OMeTAD) transport layers. Therefore, we conclude that for MAPbI3, the band tail states do not lead to nonradiative losses. ChemE/Opto-electronic Material