This essay argues that description of student learning goals as various "skills" presents a conceptual threshold lying between and connecting routinely dichotomized characterizations of student learning--most notably, "concrete" versus "abstract." Qualitative analysis of instructor interviews shows that "skills" language tends to conceal abstract (i.e. affective) learning goals behind more concrete (i.e. cognitive) ones. Ultimately, this essay proposes that cognitive and affective student learning goals might be more clearly articulated using threshold concepts within and across disciplines, and that the recognition of "skills" as both affective and cognitive is itself a threshold concept in educational development.