A Few Words About US High Schools
Education at universities lasts four years and ends with the awarding of a bachelor's degree. Most Americans at this point finish their studying and start searching for a job. Those who wish to obtain a master's degree will have to study for two more years.
By the way, in everyday speech, Americans call all higher education institutions, including universities, colleges.
In the US there is no uniform day for the whole country when the classes begin. Training programs start at different times, the dates are set by each state independently. Usually this is the end of August - beginning of September. The academic year at the universities lasts nine months. It can be divided into semesters (Fall and Spring), trimesters (three periods), and quarters. Usually exams are twice a semester, trimester, or quarter - in the middle and the end. Vacations are set by each institution. This is usually a few days off during the school time. Long holidays fall during the winter holidays and the beginning of spring.
By the way, evaluation goes through the credit system: to pass every subject you need to dial a certain number of points (credits). The final grade is composed not only of successfully passed exams. All the work of the student throughout the course is counted: attending lectures, participate in discussions, homework, etc. Criteria for assessing may be different. As a rule, they are introduced to students at the introductory lecture.
Finally we can decide what specialty to choose by the second or third year of study. Exceptions in this case are highly specialized profiles - medicine, music, engineering, etc.
To get a degree in a particular specialty, it is necessary for a student to get a certain number of credits for compulsory subjects (in the US they are called "courses"). Required courses can be clearly identified and can be selected freely, provided that the student, for example, listens to no less than six humanities courses for the entire period of study. But the most of the courses are chosen by the student himself. In each subject the student can be in the audience with different people.
In American high schools they almost don’t have lectures at all, the emphasis is on the seminars and workshops. There are several subjects, which do not include lectures; the student should have to come already prepared to such seminars, to discuss the information with other students and the teacher.
By the way
The relationship between students and teachers are generally informal. For example, a professor could sit at the table during the lecture. Students in the classroom, too, feel themselves as "at home". They can bring food and drinks to the audience and simply eat in the classroom. You can put your feet up on the desk, and you can sit cross-legged. America forgives many democratic liberties.