Which type of assessment primarily focuses on identifying a student’s previous knowledge?

The answer is correct because diagnostic assessments are specifically designed to evaluate a student's prior knowledge and skills before instruction begins. This type of assessment helps educators identify what students already know and what gaps in knowledge may exist, allowing for tailored instruction that builds on existing understanding. By pinpointing strengths and weaknesses in a student's understanding, diagnostic assessments enable teachers to create targeted learning experiences that meet individual student needs.

In contrast, other assessment types serve different purposes. Summative assessments evaluate student learning at the end of an instructional period, usually measuring the extent to which students have mastered the content after instruction. Formative assessments, while they do monitor student learning, are generally ongoing processes that provide feedback during the learning process, rather than assessing prior knowledge. Norm-referenced assessments compare a student's performance to a larger group, rather than focusing on the individual's existing knowledge base. Thus, diagnostic assessment stands out for its specific aim of uncovering what students already know, making it the correct choice in this context.