Mark Rober on YouTube performed an experiment with a 3rd grade elementary school class to see first-hand how germs get spread in public places and how the coronavirus could be spreading. Obviously, it's impossible to see germs with your bare eyes, so Rober uses this stuff called Glow Germ which mimics the spread of real germs. It is also invisible to the naked eye, but with a black ultraviolet light, you can see exactly where the Glow Germ is.
The experiment was conducted for one day of class and even the teacher had been "infected" with the Glow Germ without her knowing it. One student was also "infected." At lunch time, Rober checks out the classroom, and it is amazing to see how much the Glow Germ has proliferated in the classroom. It ends up on desks, other students, school supplies, sinks, etc. even though many of the kids were good about washing their hands.
Rober also brings up a good point about how airborne illnesses travel. Even though they can be transmitted through the air via a sneeze or cough, often times it's the water vapor droplets falling onto surfaces afterwards that poses the danger. He stresses that the single most important thing is to not touch your face.