The United States of America is a large and diverse country; nevertheless, high schools have a lot in common across the nation. In particular, mathematics teaching in American high schools, while not stereotyped, has some accepted norms which would be seen as unusual here in Australia. In order for the Australians to learn from the Americans, as well as to properly appreciate the curriculum and assessment materials they receive from them, it is important for them to understand the differences between the two countries in both schools and mathematics teaching. In this article, the author shares the differences he discovered while he sojourned in the United States to do some observations. He said that the first major difference he came across was that most schools break for nearly the whole summer; they do not resume until the start of September, which is the equivalent of March in the Australian context. High schools, in the main, cover the ninth to twelfth years of schooling; students in these years are referred to as freshmen, sophomores, juniors and seniors. This ability to spread the students across the courses is the second difference, and is enabled by the third, which is the way in which timetables are managed. He added that textbooks in the United States are usually chosen by the education district rather than the individual teacher or the school and that computer access for mathematics classes was as much a problem in the United States as it is in Australia. (Contains 1 figure.)