The scarf set the tone for the rest of the outfit. That type of red scarf was worn by youths during Mao's cultural revolution. I don't know if they're still used in this day and age, but for a long time they were worn in schools as a sign of distinction.
The slogan on this propaganda poster has been so re-iterated to most Chinese as they were growing up that it's become somewhat of an in-joke, often told in English in its direct translation.
"Good good study, day day up."
You get the idea. :)



