Assertion: "When supply of a commodity changes due to changes in other factors than price of the commodity, it is known as change in quantity supplied." This is incorrect. When supply changes due to factors other than the price of the commodity, it's called a "change in supply," not "change in quantity supplied." "Change in quantity supplied" relates to price changes.

Reasoning: "Change in quantity supplied is of two types- Extension of Supply and Contraction of Supply." This is correct. Extension and contraction of supply are indeed the two types of changes in quantity supplied, and they are directly related to changes in the price of the commodity.