American children start school at the age of five years. The first year at school is called kindergarten. It is required of all American children enrolled in the American education system. The second year at school is considered as the first year of primary school and is referred to as first grade. In the USA, the word grade has two meanings: (1) the score achieved on an exam or in a course, and (2) a year of education in primary or secondary school. Primary school most commonly consists of five years of education, referred to as first through fifth grades.