“…It consists of ordered levels, which are qualitative descriptions of observable student behaviors as thinking develops from intuitive (and sometimes problematic) ideas to conceptions that are increasingly advanced, nuanced, and precise (see Confrey, Maloney, Nguyen, Mojica, & Myers, ; Corcoran, Mosher, & Rogat, ; Deane, Sabatini, & O'Reilly, ; National Research Council, , ; Simon, ; Smith, Wiser, Anderson, Krajcik, & Coppola, ). Research on the development and validation of LPs is now widespread in the educational sciences (e.g., Alonzo & Gotwals, ; Black, Wilson, & Yao, ; Briggs & Peck, ; Graf & van Rijn, ; Steedle & Shavelson, ; van Rijn, Graf, & Deane, ; West et al, ; Wilmot, Schoenfeld, Wilson, Champney, & Zahner, ; Wilson, ), but there is relatively little research on how an important group of end users (teachers) interprets them for the purpose of assessing and guiding students (Furtak & Heredia, ). In the context of assessment, it cannot be assumed that all teachers (or all researchers) will interpret an LP in the same way, or in the way intended by the developers of the progression, and if they do not, the same student performance may be assigned to different levels of a progression by different users.…”