Which assessment compares a student’s overall achievement to that of others in the same age and grade?

The correct choice is a formal assessment, as this type of evaluation is specifically designed to compare a student's performance to that of their peers within the same age and grade range. Formal assessments typically include standardized tests that have established norms, allowing educators to interpret a student's scores in the context of a larger population. This helps determine how well a student is performing relative to their peers, identifying areas of strength and areas needing improvement.

In contrast, a behavior rating scale focuses on evaluating specific behaviors rather than overall academic achievement compared to peers. Outcome measures assess the effectiveness of educational interventions but do not necessarily compare student performance against peers. Informal assessments, while valuable for understanding a student's learning and progress, typically lack the standardized framework that enables comparison across a broad population, making them less suitable for this specific purpose.