You got some good posts from the high rollers already, so let me put this all in one easy to grasp package. First, the law will only allow a student below the college level to attend up to 1 year of public school. If your exchange student from Spain already attended 11th grade in (presumably) a public school, then the 12th grade would have to be in a private school.
Tuition is anywhere from $15K to silly money, and any private school will gladly issue an I-20 to a student who attended 11th grade in the US and has decent grades. With the I-20, she will apply for an F-1 at the U.S. consulate in Barcelona. She will have to prove that she has the money to pay for tuition plus living expenses, and then it will all go smoothly.
I hope she did not attend public school without authorization on a visitor's visa (B2). If she did, she owes the state about $11,500 and the consulate will want her to pay that before they issue her an F-1 visa. It's highly likely that they would deny her the visa because she in this case violated US immigration law.
It would make her pretty much inadmissible for any non-immigrant visa for at least several years.
It is only possible to attend public school in the US for 1 year in a lifetime if you are a non-resident. She will have to complete all of the requirements for college in her own country, get accepted, get an I-20, get an F1, and then she can come back. But only for college.
She has to return home again after college.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.