It was an old-fashioned holiday even when I was a kid. Maybe because we were out of school by then?
Flag Day commemorates the adoption of the flag of the United States on June 14, 1777, by resolution of the Second Continental Congress.
"We take the stars from heaven, the red from our mother country, separating it by white stripes, thus showing that we have separated from her, and the white stripes shall go down to posterity, representing our liberty."