elementary school

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A school for the first four to eight years of a child's formal education, often including kindergarten.
• noun The first four to eight years of a child's formal education.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun education A school for children, typically older than toddlers and younger than adolescents. In the U.S., elementary schools cover grades 1 through 5, and the ages of the children are usually 6-11 years. At a minimum, elementary schools will teach basic reading, writing, arithmetic, and history.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a school for young children; usually the first 6 or 8 grades