I truly enjoy teaching. The look that comes over a student's face when they finally understand a complex idea is exceedingly gratifying, particularly when an entire class is following. When I think about my future career, I would be disappointed if it didn't include some type of teaching.
Teaching is a integral part of an academic career and provides a benefit to both student and instructor. In my experience, the most influential researchers are also the best teachers. By learning how to present a complex topic in an obvious manner, a researcher improves his or her understanding of the problem and how it relates to other areas of research.
A college class must be presented with two seemingly contradictory goals in mind. First, an instructor should strive to provide an intuitive understanding of the topic that will permanently affect how the student thinks about the subject. Second, the necessary mathematical detail must be presented. Students that continue their studies need a solid understanding of the fundamental details of subject. To balance these two goals, an instructor should present the big picture often, including in carefully selected homework.
In mathematics and statistics, students learn through the tips of their pencils (or through their keyboards). Practice problems provide familiarity with fundamental theorems, formulas and techniques while also reinforcing the pedagogical arc of the class. The zeal for practice must, however, be tempered with a realistic expectation of a student's time commitment. A selection of problems that require a 'clever trick' should only be used if the 'clever trick' is actually an important technique or there is a useful hint in the problem.
Exams are a necessary evil. Studying for the exam allows the student to understand the individual concepts fit together. Often times, this is when the big picture finally makes sense to the student, and without the external motivation of a test, it wouldn't happen. When practical, exams should be written to push the students and explore the boundaries of their understanding. Putting concepts that have been seen in class together during an exam can have a profound effect on a student's understanding, but many students have trouble seeing connections during a high pressure situation.