  Calls to transform introductory college physics courses to include scientific
practices require assessments that can measure the extent to which these
transformations are effective. Such assessments should be able to measure
students' abilities to blend conceptually important concepts with practices
scientists engage in. To design assessment tasks that can measure these
abilities, we leveraged Evidence-Centered Design and the Three-Dimensional
Learning Assessment Protocol with the focal scientific practice of "Using
Mathematics." We conducted video recorded one-on-one think-aloud interviews to
explore how students interpreted these tasks. In this paper, we articulate our
design process and the analysis of students' responses using the ACER
(Activation-Construction-Execution-Reflection) framework. Our assessment tasks
elicited students' abilities to blend concepts with mathematics and written
solutions elicited evidence of their abilities to blend them most of the time.
This work extends our understanding on incorporating scientific practices into
paper-based assessments at the introductory level.
