noun
upper grades of elementary school
Typically refers to 5th and 6th grades, sometimes including 4th grade. Used in school settings to distinguish from lower (低学年) and middle (中学年) grades.
高学年の生徒は委員会活動に参加します。
Upper-grade students participate in committee activities.
この本は高学年向けです。
This book is aimed at upper elementary grades.