The first exercise asks students to focus on the local maxima on the
plot and to describe the contours near a maximum point. In the second
and third exercises, students are asked to consider different paths on
the plot and to describe the corresponding paths on the mountain.
Exercise 3 also focuses on a point which is a saddle point of the
altitude function. Students should be able to complete this discussion
in a single class period with time at the end to summarize their
results.