"Do your students really know what you think they know?” should be a question all teachers meeting with large classes addresses. We often rely on “assumptive assessment”, assuming because some in our classes understand everyone does. Much more valuable information is obtained through brief, regular formative assessments administered with minimal disruption to regular class activities. Attendees will learn how to address individual student mastery of all grade level standards through quick and efficient periodic formative assessments, ensuring knowledge of the level of mastery of all students. This idea can be implemented through many different online formats. Assessments can be taken on any Internet-connected device and take as little as 90 seconds, taking very minimal time away from rehearsals and normal class activities. Assessment content should be prescriptively rotated, evenly covering all the standards throughout the academic year. Results can be instantaneous and offer the teacher immediate insight into both individual and class levels of mastery. All results can be archived and collected in individual student digital portfolios. This becomes a key component of the teachers' ability to record student learning growth for quantitative data documentation of successful teaching.