Let me know when you want to speak to the subject.
You talk about testing and yet you talk nothing of how to teach children to think for themselves. how much difference is there between countries test scores? It is but a slight difference.
If teaching was a formula that could be repeated everyone would do it. Teaching involves caring for the students more than the paycheck. It is the freedom to experiment to some degree that helps some teachers. It matters when testing is of the highest expectations.
I used to tutor and gave lectures to students. I tried to get children to challenge themselves and still have fun. To be proud of their accomplishments not compare themselves to everyone else. I was not required to have a teaching degree. I even had some that skipped grades when testing began the next year.
There was not curriculum. I used the text books given to the students and added what worked best or me.
I was not raised on the US system and tried to teach my own children according their strengths and weaknesses. I wanted to home school my daughter when we moved and the school want to keep her with her age peers and not in a class that meet her abilities. My application for home schooling was turned down.
If you can turn a game of tiddly winks into an education and thought process, you do what works.
Student are not carbon copies and nor should teaching methods be.
Check with schools that have the highest test scores or that have the highest number of college graduates what their methods are.
I can't hand you a curriculum and tell you to use this.
JMHO, examples of content of standard tests for graduation should be given to the teachers and they should find their own way to make sure the student are ready, even if that means holding some back till they are ready.
I think I learned more outside of the class room than in. I moved a lot so I had to contend with not just new schools but new methods and new languages as well. Not all my classes were even in English. Often I had subjects in three different languages in a given school year, and in some cases with differing age groups as well suited my skills.
While beginning secondary school I helped my father study for his bar exams and commercial pilot captains license in the same year. His law classes were not all in the same language either. Seeing him start two new carriers helped motivate me.
I don't think there is a perfect formula. It depends on the student and the teacher. Some brains are memory oriented and some are more abstract thinkers.