Os sistemas educationais de diferentes países variam muito. Caso você deseje um termo que corresponda ao sistema brasileiro e não uma adaptação ao sistema americano, por exemplo, eu usaria o termo " Fundamental Education", como no site abaixo.

Fundamental Education (Ensino Fundamental)
Fundamental Education is mandatory for children ages 6-14. There are 9 "years" (as opposed to the former 8 "grades"). The current "First Year" broadly corresponds to the former Pre-School last year of private institutions, and its aim is to achieve literacy. Generally speaking, the only prerequisite for enrolling in first year is that a child should be 6 years old, but some educational systems allow children younger than 6 to enroll in first year (as long as they turn 6 during the first academic semester). Older students who, for whatever reason have not completed their fundamental education are allowed to attend, though those over 18 are separated from the younger children.

http://www.virtualcampuses.eu/index.php/Brazil