The Development and Scaling of the easyCBM CCSS Elementary Mathematics Measures: Grade K. Technical Report #1314.

The results of formative assessments are regularly used to inform important instructional decisions (e.g., targeted intervention) within a response to intervention (RTI) system of teaching and learning. The validity of such instructional decision-making depends, in part, on the alignment between formative measures and the academic content standards on which classroom instruction is based, as well as the technical adequacy of the measures used in RTI applications. In the following technical report, we describe the development and scaling of the easyCBM Common Core State Standards elementary school mathematics measures for use within an RTI framework. Within a given grade, math items from two distinct item pools were calibrated to a common horizontal scale using a 1-parameter Rasch analysis. The results of the scaling were then used to construct 13 alternate forms designed to be of comparable difficulty – 3 forms designated for seasonal benchmark screening and 10 designated for progress monitoring. Prior and subsequent grade-level math items were added to the benchmark test forms as a basis for constructing a common vertical scale in the future. Evidence of technical adequacy is reported in appendices by both test form and by the full bank of CCSS items piloted and