There’s a war of sorts going on within the normally staid assessment industry, and it’s a war over the definition of a type of assessment that many educators understand in only the sketchiest fashion.

Every educator knows what “a teachable moment” is. It’s the brief period of time when events serendipitously conspire to teach students something that otherwise might be difficult for them to learn.

Tests are king in many school systems and other educational environments: they are seen as an efficient way to assess what knowledge students have retained, and how well they do on a level playing ...