Many reasons.
Bad influence from other students
Bad policies for phone use
Bad teachers
Strange curricula influenced by ideology
Aggressive low performing immigrants from other cultures (Europe)
The last point will get me downvoted from people who can not handle the truth.
I am not so much worried, what position you are in. I am more worried if you are rising or sinking. The countries I was thinking in Europe are...sinking in the school rankings.
Feel free to use google translate for this example: https://weltwoche.ch/daily/wiener-schulleiter-provoziert-mit...
The problem: There are cultures that highly value education. Chinese for example. And then there are cultures where education either has much less value, or a different definition (e.g. considered highly educated if a person has memorized the complete Quran).
DEI. Diversity, Equity, and Inclusion
The "inclusion" is a problem with some cultures. They bluntly reject being "included". They considered their culture as highly superior and want to include you into their culture. At the same time, they are not able to understand why their countries are shitholes and believe that the wealth and success of Western countries is just by chance and luck and culture has no play in that.
For starters:
* Rule of law
* open society
* women rights
* Democracy
* Market Economy
* strict separation of church and state
* No tribal culture
* Freedom is speech.
* And don't marry your cousin. Your cousin may be good-looking but trust me, inbreeding won't make you smarter.
>Aggressive low performing immigrants from other cultures (Europe)
Elaborate?
https://worldpopulationreview.com/country-rankings/pisa-scor...
USA is 18th and eight of the countries above it are European. The fifteen below it have a comparable score to the USA. That is 23 European countries that are either above or around the same performance (or slightly lower) as the USA. Unless you mean Eastern Europe, which seems like a strange thing to single out