Within a global context of more standardization of teacher preparation, programs in the USA are increasingly using standardized teacher performance assessments such as edTPA to evaluate prospective teachers' instructional effectiveness and readiness for their own classroom. This study was conducted in a state recently requiring successful completion of edTPA for initial teacher certification. Phenomenological methodology was used to examine the lived experiences of six elementary prospective teachers completing Elementary Education edTPA: Assessing Students' Mathematics Learning (i.e., Math Task 4) during student teaching. Data were collected via 24 individual, phenomenological interviews at specific phases during the student teaching semester. Whole-Part-Whole analysis revealed the prospective teachers found themselves in a state of elusiveness as they engaged in Math Task 4. Three themes provide the structure for "elusiveness," including "juggling Math Task 4 in student teaching classrooms," "from relying on experts to standing alone," "and navigating edTPA processes." Understanding prospective teachers' lived experiences with Math Task 4 provides insights into both needed supports for their successful completion of the task and some of the issues with a high stakes teacher performance assessment embedded in the student teaching semester.