Briggs and Peck (2015) have written a thought-provoking article on the use of learning progressions in the design of vertical scales that support inferences about student growth. Organized learning models, including learning trajectories, learning progressions, and learning maps have been the subject of research for many years, but more recently they are being considered for and used in the creation of large-scale assessments (Almond et al., 2012; Kingston & Broaddus, 2015; Kingston, 2015). In this commentary we note an expansion of the view of learning maps presented by BP with regard to the relationships among content domains and grades. The relationships among the content domains are not so simple that a domain at one grade band leads directly into another, yet there are relationships among content standards to suggest the need to consider multiple pathways and the concept of a fine-grained learning map versus a course-grained, linear, learning progression (which is not to say that grain size or linearity is inherent in the terms "learning map" or "learning progression"). The concepts of grain size and linearity have implications for test specifications and help clarify previous debates regarding on-grade-level and off-grade-level testing. This is important, because measuring growth is not inherently meaningful if one does not allow for the measurement of precursor and successor skills.