at the height of the scientific movement, seldom took the form of controlled comparisons of the effects of teaching students randomly assigned to different groups. Marilyn N. Suydam’s (1967/1968, p. 456) evaluation of published research in elementary mathematics from 1900 through 1965 indicates that whereas one out of every three studies published in the years 1951-1965 could be classified as an experiment, in 1900-1929 only about one out of eight studies could be so classified. According to Suydam,