[elashri]

I guess it would be hard to find a high school with the sample size that you need (thousand) that will agree on collaborating. And in the US every county will have different rules and in terms of math they don't teach it in standard way.

But why Turkish not British or any other place is going to be a question no matter the location. But do you really think the results will be significantly different if it is done lets say on Vietnamese students?