Paul Black, Mark Wilson, and Shih-Ying Yao in "Road Maps for Learning: A Guide to the Navigation of Learning Progressions" provide a number of important ideas to consider regarding the development of assessments and curriculum materials to support development of core ideas. One major idea that the author found most valuable is the focus on student ideas growing over time: a growth perspective. This is an uncommon approach in assessment and instruction. A growth perspective focuses on the process of learning and how a student progresses in developing core ideas of a discipline, like atomic-molecular theory, energy, or evolution. From an instructional standpoint the growth perspective builds from a solid learning principle: prior knowledge. An individual's understanding will not occur unless links are made to prior knowledge and built from that point. Another key idea that stands out is that construct maps help structure teaching and assessment and as such help to align the learning goals, classroom instruction, and formative and summative assessments. The careful development of construct maps helps to ensure alignment among these critical elements and as such promote student learning. Although the article presents a number of rich ideas to think with, the author finds several key ideas that need further elaboration. First, construct maps should show not only how the content ideas develop across time, but how students use those ideas, as it is the use of those ideas that reveal students' cognitive understanding of the ideas. The second key idea that needs elaboration is that the development of a construct map is dependent upon the curriculum and instruction that the student experiences. More learning research is needed that focuses on students developing ideas over time in curriculum rich environments and that the development of curriculum and construct maps/learning progressions must occur iteratively. Black et al. describe how construct maps should be seen as components of learning progressions. However, the author expects to see the construct map contain ideas related to how instruction can help students move students from one level to the next level of understanding of the construct map. Although he agrees with Black et al. that there is more than one developmental progression that students might follow, he argues that there is a limited set, partially because the construct map/learning progression is limited in part by the logic of the discipline, the learning research, and the instructional components to move students forward.