Differential Equations

One of the reasons I chose the intro Economics textbook I use in my class is that they introduce the Solow Growth Model. This is a very simple differential equation model of how economic output and growth depends on the capital stock of a country. It lets you understand the world a lot better and make useful predictions about things like the reaction to a natural disaster, the results of foreign aid, and the expected future growth rate of China.

One of the well-known pitfalls of teaching a general education class is that the students have a wide range of knowledge. This is always apparent when I teach the Solow model. People who have taken a class on differential equations pick it up very quickly and end up bored by my explanation. People who do not know differential equations have real trouble following along and often need extra help.

Today, I departed from my usual question-answer format and spend most of the class explaining the basics of the Solow model, so that they would be able to follow along better when they read it in the book.  After class today, a couple students came to me and said that they did not understand and would probably coming to office hours next week for extra help.

After that, a chemical engineer came up to me and asked, "Does this mean that we will spend the rest of the semester using differential equations to model the economy?". He was clearly excited about the idea of doing so, and disappointed when I told him that this was not the plan.