The swimming of a bacterium or a biomimetic nanobot driven by a rotating helical flagellum is often interpreted using the resistive force theory developed by Gray and Hancock (1955) and Lighthill (1976), but this theory has not been tested for a range of physically relevant parameters. We test resistive...

Value-added modeling carries the promise of measuring teacher quality automatically and objectively, and improving school systems at minimal cost. Yet value-added modelingcannot be carried out without value judgments; and if there are technical errors, they will have human cost.

Metaphors play a powerful role in arguments about education. It is common to say schools are broken,and that the school system is failing. Here I take the metaphor seriously and briefly review an historical episode where airplanes failed seemingly for no reason at the dawn of the jet age. The responses...

Abstract: We use visualization to find patterns in educational data. We represent student scores from high-stakes exams as flow vectors in fluids, define two types of streamlines and trajectories, and show that differences between streamlines and trajectories are due to regression to the mean. This issue...