Volunteers will most likely be working in small towns to medium-sized cities like Zapallar, Santa Cruz, Quilpue, Limache, Pichilemu, San Felipe, La Calera and La Ligua. Inglés Abre Puertas [English Opens Doors, the Ministry of Education program] will match volunteers to teaching sites according to the needs of the schools and the experience and interests of the volunteers.
Those places are 2-4 hours outside Santiago, often closer to Valparaíso (city names have links to Google Maps with distances to the big cities). It could be that as a Spanish speaker, they'll want me to go someplace more remote (and I did indicate a preference for a not-as-big community); then again, maybe they'll want someone there who has actual teaching experience.
Now you know what I know.