Creating Reusable Educational Components: Lessons from DLESE

Reuse of educational materials is integral to many educator tasks, from designing a course to preparing for a lab or class. This article describes a study on the reuse of educational materials in the context of the Digital Library for Earth System Education (DLESE), a community-owned and governed facility offering high-quality teaching and learning resources for Earth system education. The study noted that educational resource designers often do not develop components with reuse in mind, making it more difficult or impossible for other educators to find and use their material, and that the 'findability' and reusability of community-created digital educational resources is highly dependent on the presentational and structural design of the resources themselves. The authors recommend that all resources clearly state the creator's name and contact information, relevant copyright restrictions, the most significant date for the resource (specifying creation or revision), and the intended grade level. Educational levels: Graduate or professional, Graduate or professional, Graduate or professional

Variable Appropriation of an Online Resource Discovery and Sharing Tool

Even when following best practices for participatory design, the appropriation of tools in formal education settings can be hampered by a number of factors. Drawing from a case of a web tool built to help teachers in five school districts find and share free resources in an educational digital library, we describe patterns of tool use and provide some explanations for variability in tool appropriation. We also suggest that future research consider school districts as complex systems of professionals whose interactions and inter-relationships may yield unexpected technology adoption behaviors

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data