In the January, 1998, Notices of the American Mathematical Society, Allyn Jackson reports her interview with Gail Burrill, President of the NCTM.
One small part of that report is very telling . . .
Notices: Starting in 1968, the government funded a huge study called Project Follow-Through. It cost a billion dollars and ran almost thirty years. The purpose was to examine how different teaching methods or philosophies affected student performance. What they found was that the traditional, "direct instruction" method was the most effective. Are you familiar with this study?
Burrill: I have never heard of it.
For more information on Project Follow Through, see Effective School Practices, Winter 1995-6.