The nomenclature is different in different countries. In England and Wales we start school at ages 4-5 (Scotland is a bit different again.) The first year of primary school is called 'Reception' which I guess is equivalent to kindergarten in the US. Then you go onto to Year 1, the following year to Year 2 etc. The final year of primary school is Year 6 which we finish when we are 11 years old. So we say I'm in Year 3, I'm in Year 5 or whatever year it may be. Then we go to secondary school. There used to be middle schools in certain counties (for students from Years 5 to 8, ages 9-13, indeed I went to one) but not any more, the system changed about 15 years ago. In my county there were lower schools (ages 4-9), middle schools (ages 9-13) and upper schools (ages 14-16) but these have all been scrapped and now I think pretty much everywhere just has primary and secondary schools. Secondary school is from ages 11-16 (Years 7-11.) At the age of 16 we sit exams mandated by the government (GCSEs.) Until recently you could leave school at 16. Now you have to stay in some form of education until you are at least 18. If you want to continue studying you go to sixth form college, which covers Years 12 and 13. A student normally finishes Year 13 when they are 18 years old. Then if they wish, they can go to university. Alternatively someone at age 16 can do vocational training at college (a technical school in American English) to learn to for example... Be a mechanic, be a hairdresser etc. Note that college means something different in British English. It's not used generally to refer to university education. We do not use the terms 'freshman', 'sophomore' etc. I think most people would not know what they refer to. We call first year university students 'freshers' so people would probably get 'freshman" but the others, no. The second year of high school is I believe equivalent to Year 10 in the UK but don't hold me to that.

"So I'm a 11th grader, or I'm in 11th grade." This is correct and natural. You are also "a junior" or "a high school junior." In the United States, there is no uniform national educational system. What I'm about to say is "typical." At about age 5, we enter "kindergarten." For about six years, we are in "elementary school" or "grade school." We are in the first grade, second grade, and so on. Someone might be "in the first grade" or "be a first grader." We continue through grade 12. The usual "public school" is described as "grades K through 12." It is usually broken into three schools, either called "elementary school," "middle school," and "high school," or "elementary school," "junior high school," and "senior high school." There is a great amount of silly variation in exactly which grades go in which schools. A common pattern is K through 5 in elementary school; 6, 7, and 8 in middle school; 9 through 12 in high school. Students in grades 9 through 12 are most commonly called "freshmen," "sophomores," "juniors," and "seniors," but are often called simply 9th, 10th, 11th, and 12th graders. After graduating from high school, many people go on to "college." This can be a point of confusion because in the United States, "college" always refers to higher education--the first four years of a university education. Strictly speaking, a "university" is an institution with more than one "school." The big undergraduate school, the first four years, is the "college." The rest is "graduate school" and might include a school of medicine, a school of law, a school of engineering, and so forth. In the United States we do not usually talk about going to "university" or "uni." Confusingly, the four years of college are also referred to as the freshman, sophomore, junior, and senior years. The basic four-year undergraduate degree is the "bachelor's degree" or formally "baccalaureate." We do not use "bachelor" and "baccalaureate" to refer to high school.

In South African English, we say 'I'm in Grade X'. We hardly ever say 'I'm a Xth grader'. High School starts in Grade 8 (age 13-14) and ends after Grade 12 (known everywhere as 'matric' as in 'I'm in matric'). When my parents were in school, though, they refered to each year as 'standard X' instead of 'grade X'. Except Standard 1 was equl to modern-day Grade 3, Standard 2 was equl to modern-dat Grade 4 and etcetera

In Canada, for the most part the organization of our levels of education is the same as the US (i.e. elementary school runs from grades 1-6, middle school 7-8 or 9, high school 9 or 10-12). However, we refer to the different grades in a slightly different way. Instead of saying "first grade, second grade, etc." we tend to say "grade 1, grade 2, etc." In addition, we don't tend to refer to the different grades in high school as "freshman, sophomore etc." instead we just say "grade 9, grade 10 etc." Also, what Americans call "college" we call "university" ("college" in Canada typically refers to community college, not a university). Finally, the terms freshman, sophomore etc. are also not really used in university here; instead for a Bachelor's degree we say first year, second year, etc. (i.e. "What year of university are you in?" "I'm in third year"). This is not always the norm however; for example the province of Quebec has a slightly different education system from many other provinces. I am not from Quebec so I won't try to explain it since I probably wouldn't do a very good job!

In America: If you are in your second year of high school, you would be in 10th grade (also known as a sophomore), not 11th grade. 1.Elementary School (typically kindergarten through 5th grade) 2.Middle School (6th grade through 8th grade) 3.High School (9th grade-12th grade) --> High school will also use the terms freshman (9th grade), sophomore (10th grade), junior (11th grade), and senior (12th grade). Using either the grade level or class identification is acceptable.