Transitioning from high school to college is part of the transition from childhood to adulthood. Some things will appear similar, but many will be different. Even the similarities, such as class structures and grading systems, will be significantly more challenging and difficult. The differences, such as the workload and the extent to which you'll be expected to apply yourself, will challenge your discipline as much as your abilities.
One similarity you'll find between high school and college is that classes, for the most part, will be run in the same fashion: A teacher will stand at the front of the room, teach lessons and give you exams to evaluate how much you've learned. However, in many high schools, you have all of your classes in the same time frame every day of the week, with most classes being only 50 minutes long. In college, your classes might meet once, twice or three times a week, and be anywhere from one to three hours long. Your exams could be in familiar formats, such as multiple choice, or they could be essay exams in which you write your answers in a test booklet.
Your teachers in college will be different from most of your high school teachers in several ways. First of all, they won't have the same investment in your success as your high school teachers do. High school teachers get evaluated based upon your performance on standardized tests, which don't exist in college. In fact, professors don't have any responsibility to you other than grading your work. Furthermore, college professors generally have a higher level of education in specific subjects than high school teachers, who often have postgraduate degrees in education, and so your professors won't simply be professional educators but rather potential leading contributors in their fields of study. Some might even be world-renowned researchers.
Perhaps the biggest difference between a high school education and a college education is the responsibility you'll undertake as a college student. In college you are an adult, and you will be held accountable for all of your behavior. Nobody will force you to go to class or study for your exams, and your professors won't be nearly as willing as high school teachers are to negotiate grades. In high school you are trained to follow rules: Class attendance is mandatory, and your teachers always tell you exactly what you need to do and know. In college, you have to prepare yourself: You choose which classes to take, and you might not always be told what information will be on a test.
Atmosphere and Social Life
The atmosphere and social life in college is also significantly different than in high school. For example, if you go to a large university, your campus will be your home and might take up an entire town. You might see hundreds of students going out to bars every night. Many colleges also are home both to academic and social clubs, including fraternities and sororities. Your campus also will provide you with massive libraries, advanced laboratories and other facilities you won't find on any high school campus. The scope is larger. In high school your stage is predominantly regional. In college, your stage is national, and sometimes global.