Island of the Blue Dolphins is a great book. It is, of course, a book of fiction so there is no absolute answer to your question. O’Dell grew up along the California coast, primarily in San Pedro. The Channel island of San Nicholas is about 52 miles off the coast, west of San Pedro.
Most literary scholars believe that San Nicholas was the inspiration for this book, because of where O’Dell lived and because of the island’s size, its abundant sea life and it’s history (a band of Kodiaks did land on the Island in 1811). There was also a real life story involving “The Lone Woman on San Nicholas Island” which you can read about in the California Stories section of our website.
Unfortunately San Pedro is a long ways from San Francisco and there isn’t a mission there.
What I think the teacher was probably remembering is Mission Santa Barbara, which also has Channel Islands off its shore. The Lone Woman of San Nicholas was brought to Santa Barbara after she was rescued. She was given the name Juana Maria and she was, in fact, buried in the cemetery of the Santa Barbara Mission.
While a little closer, Santa Barbara is also not convenient for you to visit unless you are planning a drive all the way down the coast. There are six mission within striking distance of San Francisco. You can get a sense of each of them by playing the Flash movies on our website (go to Mission Gateway, the Visual Journeys).
While they all have their attractions I think Mission San Juan Buatista would be my first choice although it is a bit of a drive (about 70 miles as I recall). This is a charming mission set on the only original Spanish Square left in California, and there are a couple dozen historic buildings in the adjacent State Historic Park. Kids love this mission.