Understand that "elasticity," the responsiveness of quantity to changes in price, is an important concept in economics.
Recognize the relationship between the concept of elasticity and the appearance of the demand curve.
Understand and show that a market equilibrium provides both buyers and sellers with benefits. Consumers pay less than they are willing to pay and producers make a profit. Economists call the former "consumer surplus" and the latter, "producer surplus."
Recognize "dead weight loss," a circumstance which comes into play when prices that are too high or too low create inefficiencies.