How did signing of casts start?

in high school in the sixties, we signed casts. I don’t recall signing cast in grammar school

Makes the person with the cast feel “special”—that and you have this fairly permanent thing (well, I kept my casts for a while) to remember all the folks who were around you then =)

….bpeoples said; Makes the person with the cast feel “special”—
Had a physics teacher sign casts in a big red marking pen,
“When you’re stupid, it’s for a long time”....
Didn’t really answer the question, jogged the old memory bank though…

I had people sign my cast in grade 5…in the 80’s