Gotta chew on this one.
Sample questions from Singapore's PSLE examination. This examination is given to sixth graders who leave for secondary school. Apparently secondary school starts after sixth grade in Singapore. I can't imagine giving these types of questions to most sixth graders here. At least not at this point.
Apparently, this kind of proficiency can be achieved with Singapore's cheap math booklets.
It ain't the money, it's the quality of the curriculum and instruction.