**Learning objectives**

- Interpret second derivatives
- Understand relative rates (such as birth rates)
- Understand elasticity (such as price elasticity of demand)

**Before class**

- Read Hughes-Hallett 2.3 (relative rate of change), 2.4, 4.6
- Ponder problems 2.3. 42, 43, 44, 46; 2.4. 2, 10, 20, 26; 4.6. 1, 2, 3, 4.
- Consult the main points of the lesson.
- Consult notes on two types of change and three derivatives

**.In class**

- Work on problems from the textbook.
- Graphical differentiation