Secondary education in the United States is generally split between middle school and high school. The term high school usually refers to grades nine through twelve, in other words, from the age of thirteen or fiftteen to seveteen or eighteen. A class period is the time allotted for one class session. In high school a period may vary in time, but is usually around forty or fifty minutes long.
9th Grade - Freshman Year Starting at 14 to 15 years old
10th Grade - Sophomore Year Starting at 15 to 16 years old
11th Grade - Junior Year Starting at 16 to 17 years old
12th Grade - Senior Year Starting at 17 to 18 years old (This would make a student graduate at 17 or 18 years old)

Now, let's see what a school day in high school looks like. As we can see in movies there are yellow school buses, lockers, cafeterias and cheerleaders. They attend different classes, join clubs and sports teams and participate in a "Prom" at the end of the year. U.S. high school is a community which meets for small and great events such as American football games on a Friday night.

You can choose extra-curricular activities like : basketball, swimming, cheerleading, playing in an orchestra, acting or even writing articles in the school newspaper.

A typical day in a high school :

7:40 a.m. (at twenty to eight a.m.) :They hang out with friends before school in the lockers area.
8:00 a.m. (at eight o' clock) : First class. This may be english, mathematics, history or something different like photography. Every morning American pupils pledge allegiance to the flag at school to show honour and respect to their country. (compulsory in 35 states)
9:40 a.m. (at twenty to ten a.m.) : Second class. It could be science, foreign languages, drama or sports.
10:20 a.m. (at twenty past ten a.m.) : They have a break. Discuss with their friends while they tidy up their stuff in their lockers.
10:30 a.m. (at half past ten a.m.) : Third class
11:10 a.m. (at ten past eleven a.m.) : It may