Using twin studies, Ashenfelter and Krueger found that estimates of this practice’s effects can be biased by measurement error. A “transformative” form of this practice results from a “disorienting dilemma” according to Jack Mezirow. Jerome Bruner integrated another model to create a “spiral” version of this practice by including an “exploration” element. Psychological elements like abstraction were identified within (10[1])four “planes” in a method of this practice applied at the Casa dei (10[1])Bambini. (10[1])Benjamin Bloom created six goals for this practice, his namesake “taxonomy.” (10[1])Raj Chetty et al. found that Project STAR, a Tennessee experiment about heterogeneity in this practice at early ages, has significant effects on future income. For 10 points, name this practice, which psychologists study using the Montessori method. ■END■