For my next trick, I'll slay Brad's other sacred cow: constructivism. Is it a useful pedagogy for teaching novices with little domain knowledge? I say no.
Update: Brad posts a letter from a lead-poisoning researcher who discusses the effects of lead poisoning on IQ. Lead poisoning is a bad thing. Fortunately, at levels where it becomes a known medical problem it is exceedingly rare. However, recently activists have been claiming that even tiny levels of lead exposure cause damage and may affect IQ. Unfortunately for theactivists, those "studies" are junk science:
As was pointed out in the New England Journal of Medicine, “...the investigative bodies found Needleman’s studies scientifically flawed... involving a ‘pattern of errors, omissions, contradictions and incomplete information...’ The University of Pittsburgh... stated that had Needleman accurately described his methodology and subject selection, he ‘would have risked rejection’ of his article by the New England Journal of Medicine. In addition, the [federal] Office of Research Integrity cited misplotted graph points, which were found ‘difficult to explain as honest error’...”
Subsequent studies, generally conducted by activist-researchers such as Lanphear, purport to support Needleman’s original claims. But the studies suffer from the same basic flaw: their weak statistical associations between blood lead levels and learning and behavior problems could easily be explained by socio-economic factors not adequately considered by the researchers.