Math(yes math) Goofs

2 math goofs

In Episode 11, right after he gets the text message. 29:30 into the movie
The teacher asks "Can anyone tell me how to calculate the surface area of a circle?"

Circles have area, not surface area. 3 dimensional objects(cubes, spheres, cones, etc) have surface area.

The teacher then gives the answer as "two pi r" (2*pi*r) This is the formula for the circumference of a circle(not area)