A few years ago, Harris promised his sister, Kaylin, that he would speak at her school's Memorial Day program, but he was called away to training and later died in Afghanistan.
On Friday, members of Sergeant Harris' unit visited the school.
Illinois Gov. Pat Quinn, who was at the event, called the soldier a hero.
"He had a purposeful life. He understood that being a soldier was a special vocation, a vocation of protecting others and protecting our democracy," said Quinn.
Sergeant Harris' unit members also presented Kaylin Harris with a gift in honor of her brother.
