A completely not bogus formula for the Blackboard Stupidity, or BS, factor. Image: Evelyn Lamb.
In this formula:
n=number of students in the class;
s=number of hours of sleep you got last night;
p=number of hours of preparation you did for the class in the past three days;
m=”morning factor”=number of hours before noon of the class start time;
d=distance between your forehead and the blackboard, in meters.
Evelyn Lamb, Blog, Scientific American, 31 augustus 2013.