Complex sentence: Her time at Harvard is what led her to further research on methods of testing infant's IQs and while at Stanford she did work with Lewis Terman on the Stanford Achievement Test and the development of a masculinity-femininity test.
Split into simpler sentences: Her time at Harvard is what led her to further research on methods of testing infants' IQs. While at Stanford she did work with Lewis Terman on the Stanford Achievement Test and the development of a masculinity-femininity test.