In the United States, the terms "primary school," "elementary school," "middle school," and "high school" are used to refer to distinct levels of education.

• Primary School: This term is not commonly used in the U.S., but it typically refers to the first stage of compulsory education, generally encompassing students from kindergarten to around the age of 11. In the U.S., this would be equivalent to elementary school.

• Elementary School: This usually spans from kindergarten or 1st grade through 5th or 6th grade, covering children aged approximately 5 to 11.

• Middle School: Also known as junior high school in some areas, typically includes grades 6 or 7 through 8 or 9, for students roughly aged 11 to 14.

• High School: Encompasses grades 9 or 10 through 12, with students aged about 14 to 18. It is the final stage compulsory education and prepares students for higher education or the workforce.

It's important to note that these terms and the grade levels they encompass can vary slightly by region or school district within the U.S.