Here is a very good illustration of it.
This is a very common scenario in every student who finds studying or a subject or a lesson boring. Another thing that adds to this boredom is when your professor is a lifeless human being standing in front of the class. Reading out aloud or discussing in a very solemn rhythm at the rate of 60 words per hour or 1 word per minute. Man, it is tough being trapped in this class. *sigh.