After one look at the pristine pools packed with toys, and it’s no surprise why La Petite Baleen’s four San Francisco–area swim facilities are so popular with kids. What may be surprising, however, is that the flourishing network of schools started humbly in the backyard pool of John Kolbisen and Irene Madrid.

In 1979, the public school teachers were brainstorming ways to integrate their passion for educating kids with their love of the water. Starting with their own three children, some neighborhood kids, and their logo–Waverly the Whale, John and Irene began teaching swim lessons with a rather progressive philosophy: They approached swimming not just as an extracurricular activity, but as a means to boost self-confidence, build friendships, and learn to overcome fears.

More than 30 years later, La Petite Baleen has become a renowned family of schools, partnered with the U.S. Swim School Association and the Swim for Life Foundation. Part of the success has to do with how children are grouped. In weekly sessions, pods of tots of similar age, skill level, and personality evolve at a similar pace—earning individual achievement ribbons as they do. Kids make friends in the group, and the recurring scheduling means that they can stay enrolled with their new buddies indefinitely or until they grow their own dorsal fins. Each location’s indoor pools are kept at an inviting 90 degrees, in an attempt to make even the most timid student to feel comfortable in the water. Perhaps most importantly, the teachers participate in ongoing training designed to encourage empathetic, yet firm teaching methods.