While reading comments between you and Doug I noticed mention of the 'maturity' of college students. Having taugh physics, calculus, chemistry, organic chemistry, anatomy&physiology and a few other science courses during the 8 years I taught at the college level, I can say that my experience with foreign-exchange European students studying here in America is that they are an exceptional lot.
One, in particular, stands out. He was a French highschool student who was to attent the local high school for his senior year. He tested out of everything the highschool offered so, in desparation, they brought him to the college where I was teaching. He tested into Calculus II and Engineering Physics. During that year he held the top grade in both classes. His english was better than the American students, as was his writing. Local idioms confused him at times, but that reflected more on the stupidity of the idioms than his lack of education. At the end of the year he was visiting in my home and I asked him what he was going to major in when he returned to France. He said, "I am not going to college." I ask "Why?" He said "I am not good enough to get in." I was stunned. He was head and shoulders above American students boasting ACTs of 33. He said he was going to what would be considered here a vocational-technical (votech) school.

A German student was equally talented and went on to obtain his PhD in entomology. Over the years I had 5 students from Saudia Arabia who were not very academic at all. The problem was that in their culture is was acceptable to barter (bribe) for grades and I heard the phrase "Mr. Kreps, I deserve A, not C" more than once. In discussing why our cultures were different, they dismissed the need to "know" because they each received a portion of the oil wealth and would hire folks to "know" how to do what needs to be done. One told me that every Saudi received a free house too, but I don't know if that is true or not. I don't believe this attitude was held by all the Saudi's however, because I've read some good papers written by their more serious scholars.