Final answer:
A teacher is likely using a rubric to score student writing samples by outlining clear criteria for different proficiency levels.
Step-by-step explanation:
A teacher who scores student writing samples using criteria that define expectations for different levels of proficiency is most likely using a rubric. A rubric is a scoring guide that provides a detailed description of what is required for each level of performance. This tool helps teachers evaluate work by clearly outlining the criteria for each score, which can include aspects such as clarity, organization, content depth, grammar, and more. Teachers use rubrics to maintain consistency and objectivity in grading, as well as to provide feedback that helps students understand their strengths and areas for improvement.