You cannot take a bus from South America to North America. Many Bolivians speak only Quechua or Aymara. There is a 99 mile gap in Panama's southern province of Darien that has no connecting roads on to Colombia. This is intentional, because of the fact that S. American cattle and other livestock are carriers of diseases that are fatal to Central American and N. American cattle and other animals. Cows, goats, sheep and chickens are not native to S. America, but llamas, guanacos, vicuñas and several species of deer are, and they have infected cattle in the past, and now the cattle are immune. But N. American cattle are not.
http://en.wikipedia.org/wiki/Darien_GapHistorically, Panama, being a part of Gran Colombia and later Colombia until 1903, is politically part of S. Americas. Geographically, it is a part of Central America.
Panama was pressured not to build an expensive highway through the Darien because of the possibility that Panamanian cattle would become infected,and cause epidemics further north. You CAN take a canoe during some seasons of the year and hike through the Darien, but no one who has done it recommends it that I have heard of. Spanish would be problematical among the Panamanian and Colombian Indians in this area.
No college would permit any of these suggestions.
I never graded anything on a curve. Any instructor who does not know what his students are capable of learning if they study the proper amount should ever do this, in my opinion. As I said, class attendance was the major factor in students failing my classes. Not studying enough (or at all) was another, and then there were those who refused to buy the book. I could refuse to ask questions of those who had no book in class, and did so, giving them an F in oral participation, but some simply used someone else's book and never bothered to study any book at home. I always had a copy of the textbook in the library on reserve (meaning they had to use it there), and told everyone about it in the course outline or if they came to my office to plead poverty, but I did not announce this in class, because when I did, the book on reserve somehow got stolen from the library.
Grading on the curve is a stupid practice, as it tends to diminish minimal standards. Perhaps it could be justified for one semester at most, until the instructor figures out exactly what the students are capable of. I didn't do it, ever.