Why is the second class in a subject called [Subject] 201 instead of?
In my experience, a topic 101 was the first year and if it continued in the first year it would be 102. Then a more advanced class for the second year would be 201 and 202. Other branches of the same subject would be labeled with differences in the tens column. For example, taking Economics. First year general economics would be Econ 101. First year economics of developing countries might be Econ 121 and so on.