Last year, an English teacher at my school came to me with an all-too-common concern about an essay a student named Kyle had just turned in. The teacher’s 10th-grade class had just finished op-ed essays on a topic of their choice, and Kyle had chosen to examine the economic impact of illegal immigration on the U.S. economy. But in his submitted draft every source in his bibliography—and I do mean every—leaned toward one political bias, and sometimes quite heavily.

“It happened again,” lamented my colleague.

Despite directing the class to consult disparate points of view and guiding them to databases and websites constructed to provide point and counterpoint arguments, ...