Thanks, Georgina for your suggestions regarding the airline ticket from Nicaragua.
But just now I learned that I cannot predict when my Spanish teacher will even be able to get her educational visa to come here to study English.
We contacted a local English school which originally told me it would take 4-5 days to get the visa. But now that we submitted our application to them they said they will overnight her a letter of acceptance and a completed I-20 and then she must go to the US Embassy in Managua and request a visa. There is no way to know how long it will take to get the visa: it could be issued on the spot or she could wait months.
So I cannot really book a flight until that visa is issued. And since she is staying for several months I guess I will be subject to the double fares that some airline MBA figured they could soak passengers for who stay away for more than 30 days---and they can because I am willing to pay.
Hamlet