The most important thing is to adapt the way to learn, or process in the US system guideline. Oh, I wrote opposite. For teachers and students it is important to study anything they want. What I want to tell you, Japanese schools are not doing this way. Before students want to learn something, it is clear that they have to learn at the time in a year or totally in elementary school education.
Japanese government decide one guide line for school education.
And textbook publishers made the textbook. City or town educational part selects the textbook and give students for free. So teachers and students have to use the textbook to be given by local government. So all the year, in all part of Japan, students learn all the same thing, even if it is the place so cold and so hot. And most fun thing is to have to learn the same textbook even if they are not in Japan.