**Learning objectives**

- Explore the chain rule for compositions of functions with various numbers of variables
- Treat the chain rule as substitution into differentials

**Before class**

- Read Hughes-Hallett sections 14.6.
- Ponder Hughes-Hallett problems: 14.6: 3, 9, 15, 17.
- Complete HW4 on WeBWork
- Post to Piazza
- Write solutions to problems 14.1: 26-28; 14.2: 42; 14.3: 26; 14.4: 68; 14.5: 44, to turn in at the beginning of class.

**In class**