• Measuring slope along various directions at a point on the surface
• Experimentally verifying the chain rule relation: $\frac{\partial f}{\partial r}=\frac{\partial f}{\partial x}\frac{\partial x}{\partial r}+\frac{\partial f}{\partial y}\frac{\partial y}{\partial r}$

Estimated Time: 20 minutes

See handout on activity page.

• Familiarity with the multivariable chain rule

• Tabletop Whiteboard with markers
• Surface Kit
• A handout for each student

• Some students may be confused by the (lack of) dimensions of slope