Documentation:Clickers/Ab 0 Score iGrader
Q: What is the difference between a score of Ab and a score of 0 in i>grader?
A: A zero indicates that the student did respond in class but did not meet your requirement for earning points. Ab (absent) indicates that the student did not provide any responses for a session. A student who missed class or did not answer any questions would receive an Ab. This value is treated as zero points for calculating averages, but is displayed differently to indicate at a glance that the student did not participate or was not in class.