The teaching of renal physiology is an ever-evolving and fascinating opportunity to learn as well as to teach. Regardless of the particular format of our teaching, a constantly waxing tide of detailed information forces us to be selective. We cannot teach it all. In my own lectures and discussions of renal ion and water transport systems, I try to 1) avoid complex and detailed areas that are not essential to a basic understanding of renal function, 2) highlight the commonalities of transport processes among segments, 3) relate the details of transporters to clinical conditions that are especially interesting, 4) make connections between physiological details and clinical therapy, and 5) stress quantitative problems. Although generally simple, the quantitative understanding is essential to appreciate the role of the kidney in homeostasis and derangements thereof. When I review what I have taught, I try to integrate multiple basic mechanisms in individual segments to produce a picture of "whole kidney" function.