Where I live, police can and will ticket you for speeding during those times. Regardless of if there's students around or if school is even in session or not.
https://www.pressdemocrat.com/article/news/what-does-when-ch...
> On a school day when school children are present and so close thereto that a potential hazard exists because of the close proximity of the motorized traffic
this lawyer https://www.jolietlaw.com/will-county-attorneys/understandin.... claims that means the limit is not in effect when kids are inside
Can be times of day, "when flashing", or "when children are present". Time of day isn't great because of irregular after school activities, events, delayed starts because of snow, etc.
https://www.dot.ny.gov/about-nysdot/faq/posting-speed-limit-...
On my daily commute, there's two overhead flashing yellow lights. Previously, my Model Y would begin to brake and then speed back up, thinking it's a normal traffic light (prior to FSD). With FSD, it's at least smart enough to know not to brake; but it certainly doesn't read the speed limit from the sign, as it normally would.
Depends on the locale. A lot of places just say "Speed Limit is X When Children Present", or "Speed Limit is Y when Lights [on the sign] are Flashing".
In my local area the signs say either "during school hours", "while children are present" or they say nothing at all and you just have to know what hours and days the lower speed limit is enforced.