From the website; "This is a tool to help understand COVID-19 transmission risk to students and teachers/professors due to transmission by microscopic airborne particles (i.e. aerosols) in classroom settings. This is not an infectious disease dynamics model, but rather a model that predicts airborne virion concentrations within a classroom, taking into account exhalation of virion-containing aerosols by infected individuals and the loss of these particles due to various processes. Probabilities of infection are calculated based on the virion dose inhaled (accounting for use of masks) by uninfected people in the classroom."

Take a look and see if the math is correct. From what I'm finding, it comes real close...

http://covid-exposure-modeler-data-devils.cloud.duke.edu/?fbclid=IwAR2xqNlK695UeeedrNif_UeO48T3x8IylcbOsJfYaqEXLNIhr7flJTO_BxQ

interesting...so, using a full school year and full class of 30 kids, the chances of infection are about 10% for the teacher and 10% for student.

I see where this does not take into account "droplet"...only aerosol. This would seem to lower the real risk factor causing the % to be lower than normal?