Class size characteristics at the National University of Singapore (NUS).

(A) The distribution of class sizes is shown for the second semester of the 2019/20 school year in which the COVID-19 outbreak occurred. Class sizes were categorised as small (green; ≤25 students), medium (blue; >25 to ≤50 students), or large (red; >50 students). (B) The combined student enrolment in medium and large classes was greater than enrolment in small classes. (C) The cumulative distribution plot shows the number of students whose smallest class of the day exceeded a given class size threshold. The black trace with shaded grey lines shows the daily mean and range. The red dropline shows that the transition to e-learning for classes with >50 students resulted in about 5,000 students per day who had classes delivered only by e-learning. The blue dropline shows that the transition to e-learning for classes with >25 students resulted in about 9,000 students per day who had classes delivered only by e-learning. When all classes were shifted to e-learning there were about 18,000 students per day taking their classes online.

(TIF)