Re that article on reopening universities in the fall: let's just talk about the basic mathematics of physical distancing while students are entering and leaving a classroom.

At UBC, there are 10-minute breaks between classes. To start, assume a class of 60-70 students. This is a *small* class, by UBC standards. Often taught in a classroom with only one door.

Let's say 60-70 students need to exit that classroom maintaining a 2m distance from each other. You have to give them 8-10 seconds per student, for one door. That's 6-8 students per minute. The process of leaving classroom takes up the whole 10-minute break.

But wait, we are not done. The teacher needs to erase blackboards, gather any materials used - all while maintaining the distance, how? will there be barriers? and exit. Then the next class has to enter - another 10 minutes.

This was the "good" scenario. 60 students is a *small* class. A large class at UBC has 200-300 students. It can easily take more than 10 minutes to get from one building on campus to another, so we need another 10-minute break for that.

And that's before we get to the *real* bottlenecks, which are building entrances and staircases. One class is already a crowd. There are many of those starting and ending at the same time in the same buildings with few entrances.

Every sensible plan for reopening a workplace, such as these https://www.washingtonpost.com/business/2020/04/23/offices-after-coronavirus/ accounts for the bottlenecks at entrances. For example, work hours are staggered so that people do not all enter or leave at the same time. Can't do that with in-person classes.

And, no, not all classrooms have a second door. Many UBC buildings are seriously outdated. Large classrooms with more than one door also tend to hold larger classes. Do the same math, and the problem still exists. https://twitter.com/BrKloeckner/status/1254494673088937985

I've taught a class of ~60 in this classroom. https://learningspaces.ubc.ca/classrooms/math-102 Nominally, two doors, but right next to each other so still crowded.

Just one of the things that, say, a provincial govt might not know. But instructors sure do. ASK US BEFORE YOU DECIDE IF IT'S SAFE.