system
Given the following post, respond as if you're commenting on Reddit:
human
I'm a teacher with a very simple question on supply and demand.

I teach social studies and this year, I was given an economics elective. Teaching this is very new to me. We are doing supply and demand and my students are VERY confused. I feel I am failing them because there is really only one way that I can explain things. I have two questions.

Here are two examples of questions:

1. *"In a small-town store, shoppers can choose between vanilla ice cream and chocolate ice cream. Everybody likes both equally, so they will buy what is cheapest. The price of chocolate ice cream has recently doubled, making vanilla ice cream much cheaper."*
2. *"As a result of the recession, numerous shopping malls have shut down, dramatically reducing the number of seller of clothing."*

In the first example, demand will increase and supply will stay the same. However, my students CAN NOT understand why supply does not shift here.

In the second, supply should decrease and demand should stay the same. Again, they cannot understand why a decrease in supply would not change demand with it.

I believe the whole "change in supply/demand" vs "change in quantity supplied/demanded" is really tripping them up. Can someone help me explain this to them?
gpt
Change in quantity supplied/demanded is always in response to a price change. Graphically, this is a movement along the supply/demand curve. The key thing is that underlying preferences (or for supply, production costs)  for the good haven’t changed, only the current price. Everyone still feels the same about each ice cream flavor, but they are facing a new price so they want to buy/sell a different quantity.

Shifting the curves means the relationship between price and quantity has changed. These are changes in supply/demand. This would be if people decided that they like ice cream more than they used to, or if a study came out saying ice cream causes cancer (making people like ice cream less). Even if the price stays the same, they want to buy a different quantity.