In the early 1970’s, back before MLK day was a holiday in California, I was in High School and as I approached my school (George Washington HS in San Fran) there were about 200 Blacks and about 20 white liberals protesting and wouldn’t let me cross the picket line and called me a racist simply because I wanted to go to school that day.
I imagine even back then, those 200+ kids got an excused absence for that missed day of school while us kids that went to school and did our school work were graded based on our work.