Report: Singapore Math Works
There is an interesting website devoted to reforming math education in Utah; it is utahsmathfuture.com. On it, among other text and video content, there are links to reports about a longitudinal study in a Massachusetts school district showing the improvement in test scores over the long term when the district adopted Singapore Math. The evidence is compelling, not only qualitatively but quantitatively. I have also provided the report for download here.