primary school (or elementary school in American English and often in Canadian English) is a school in which children receive primary or elementary education from the age of about five to twelve, coming after preschool and before secondary school. (In some countries there is an intermediate stage of middle school between primary and secondary education.) In most parts of the world, primary education is the first stage of compulsory education, and is normally available without charge, but may be offered in a fee-paying independent school. The term grade school is sometimes used in the US, although this term may refer to both primary education and secondary education.

The term primary school is derived from the French école primaire, which was first used in 1802.

Primary school is the preferred term in the United Kingdom, Ireland and many Commonwealth nations, and in most publications of the United Nations Educational, Scientific, and Cultural Organization (UNESCO).

Elementary school is preferred in some countries, especially in the United States and Canada.

In the United States, "primary school" may refer to a school with grades Kindergarten through second grade or third grade. (K-2 or 3). In these municipalities, the "elementary school" includes grade three through five or grades four to six.

In some places, primary schooling has historically further been divided between lower primary schools (LP schools), which were the elementary schools, and higher primary schools (HP schools), which were established to provide a more practical instruction to poorer classes than what was provided in the secondary schools.

rade跟year差一，真让人困惑。The primary school years are split into Key Stages:

Nursery, age 1 to 4

Reception, age 4 to 5 (Pre-K)

Year 1, age 5 to 6. (K)

Year 2, age 6 to 7 (1st grade)

Year 3, age 7 to 8 (2nd grade)

Year 4, age 8 to 9 (3rd grade)

Year 5, age 9 to 10 ( 4th grade)

Year 6, age 10 to 11 (5th grade)

At the end of Year 6 all children in state primary schools are required to take National Curriculum tests in reading and maths also called SATS.

They then change schools to go to secondary school.

Year 7, age 11 to 12 (6th grade)

Year 8, age 12 to 13 (7th grade)

Year 9, age 13 to 14 (8th grade)

Year 10, age 14 to 15 (9th grade)

Year 11, age 15 to 16 (10th grade

Year 12 (6th form), 16 to 17 (11th grade)

Year 13 (6th form), 17 to 18 (12th grade)