In most cases i've seen it's like this:
Blue - (insert your country's language)
Red - Math
Green - Science
Yellow - History & Geography
For other subjects it varies from school to school.
I feel like for me it's always...
Green - science
Blue (but less often red) - math
And everything else varies
Yep the language/elective got the more unconventional color, and blue was the socials/history/humanities
In my times I don't recall such association, so I'm making this up.
It depends a lot of the curriculum, but I'd try something like:
Philosophy, computer stuff, civic order, similar: no idea.
From my perspective in Germany:
Color? In the USA we don't have such standard. We had multiple colors for the same subject from teacher to teacher or year to year. Sometimes colors overlapped.
Language Arts- dark yellow. Science - bright blue History and Geography- green Math - red Religion - purple Mine is probably different because I was homeschooled, but other people who were homeschooled may agree.
English - Blue with yellow sticker
Spanish - Purple with pink sticker
Math - Green with orange sticker
History - Orange with green sticker
Bio/Chem/Physics - yellow with pink sticker
Elective - Red with green or yellow sticker
I left high school literally 20 years ago, and I still remember the colors!
🔵 Math 🟢 Science 🔴 Portuguese 🟠 History/Geography
Brazilian here. I've always associated this colors to this subjects. I guess our books were color themed or something.
From my American high school subjects in no particular order:
English - Navy Blue
Science - Green
Math - Orange
History - Burgundy
Spanish - Red
Band - Brown
Gym - Yellow
Art - Salmon
Latin - White
Computer Science - Gray
Study Hall - Whatever color you see when you close your eyes, because that's mostly what I did.
I used to have them all color-coded so I could keep my notebooks organized. I do not remember the colors and I threw those out ages ago.
Biology - Green
Math - Purple
Physics - Blue
History - Brown
English - Red
Chemistry - White
Math: Red
Science: Green
English (Native Lang:) Yellow
Social Studies/History: Orange
Health/Sex Ed (in high school they were the same:) Purple
Phys Ed: Beige
Programming: White
Art: Manila
Spanish: Also Green
French: Also Blue
Music: Also Purple
Currently for me it's like this:
In College, for folders
anything Roman=Red
anything Greek=Green
English/Literature etc.=Orange or Yellow
Latin=Red or Yellow(depending on if I'm taking another Red or Yellow course, I never took enough classes to cause a conflict)
Math=also Red, but Latin or Roman stuff takes precedence
Science=blue
Anything else=whatever's not already used
Red: Cantonese Blue: English Green: Mathematics Purple: Sciences Beige: History
After a while it all broke down tho
Red for English/language arts Blue for math Green for science Yellow for geography/social sciences/ history