There is a cynically and incredibly foolish expression, “Those who can, do; those who can’t, teach.” Yes, it is grounded in the idea that many teachers are not the deepest content experts. However, it is foolish for two reasons. First, it entirely misses the fact that good teaching requires its own set of skills—skills that mere content experts usually lack. Second, and perhaps less obviously, it misses the fact that teachers must have a different relationship to the content than mere practitioners—even those at the highest level of experts who practice with the most nuance, skill and wisdom.
Teaching requires thinking about the content, holding it at arms length, rather than just using it. Some (e.g., teachers) call this meta-cognition, thinking about thinking. Being able to do does not require consciously understanding what it is you are doing or being able to communicate to others. In fact, that kind of thinking can get in the way of fluid skillful practice. It does not require understanding how others might do the skill. Teachers have to understand the kinds of mistakes that learners make, and the different learning paths towards proficiency.
Content development work for large scale assessment (e.g., standardized testing)—the work of crafting and refining the contents of tests—requires many of the same skills as teaching. It requires thinking about the content. Like teachers, content development professionals (CDPs) need to understand how others understand the content, and the ways in which they might misunderstand or misapply it. They need to be able to recognize their own thinking and learning path, but not be so self-centered as to assume that it is the only learning path. Like good teachers, they need the empathy to imagine the cognitive paths of others—including those with vastly different backgrounds and experiences.
Yes, and like teachers, CDPs need content expertise. And like teachers, they need far deeper content expertise than most people realize. They need to understand how the content fits together and how it is applied in practice. They rarely have the fluidity of a practitioner’s mastery at the highest level of professional practice, but they have deep understanding of content, nonetheless.
And they also need many of the expertises of teachers, in addition to their own particular additional skills, knowledge and abilities.