an elementary school that has its pupils grouped or classified into grades.
Also graded school.
Origin of grade school
An Americanism dating back to 1850–55
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for grade school
Contemporary Examples of grade school
Just recall that grade-school lesson about the Dutch grabbing Gotham for a string of beads.The New Corruption Capital
Samuel P. Jacobs
March 3, 2010
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012