This study examined how the relationships between one observation protocol, the Protocol for Language Arts Teaching Observation (PLATO), and value-added measures shift when different tests are used to assess student achievement. The findings revealed that PLATO was more strongly related to the Stanford Achievement Test (SAT-9), the alternative assessment used by MET to assess more ambitious outcomes. Furthermore, the authors found that the SAT-9 is more instructionally sensitive to the PLATO factor of Cognitive and Disciplinary Demand than the state tests used in MET study.