Correct Response: C. In the scenario described, the teacher makes an instructional decision—to make vocabulary instruction more systematic and robust—based on students' performance on the vocabulary subtest of the standardized schoolwide assessment. Their performance was below the national average and, more importantly, below their performance in other dimensions of reading measured by the assessment. Option A is incorrect because the scenario does not provide information about the students' performance on informal assessments. Options B and D are incorrect because the scenario only mentions the standardized schoolwide assessment and does not provide information about other assessment strategies the teacher is using (B) or whether the results on the standardized assessment provide information about how the students performed with respect to state standards (D). The scenario only mentions that the students performed "below the national average."