And if you do already know about it, let me tell you about one of my wife Peggy's and my most memorable Elderhostels. In the U.S., programs last one week, and usually consist of 3 courses. Each course may be given for an hour each morning, with field trips in the afternoons.
Overseas programs are longer, lasting two to three weeks.
To keep costs down, accommodations may be in motels or college dormitories, and meals may be served in college cafeterias. We have had no complaints with the food or the accommodations. Since we live in Southern California, in an earthquake zone, we were very interested. The Southern Alps, on the south island of New Zealand, is a great place to become acquainted with geology, we felt. After that first exposure, we wanted to learn more about the earth we live on.