As complex and theoretical as constructivist principles sounds, classroom application often boils down to two precepts. First, learning is an active process—it does not happen passively. Learners need to mentally process new ideas to assimilate or accommodate them into cognitive structures. Second, transitioning misconceptions toward scientifically accepted ideas involves recognizing deficiencies in the current way a student thinks combined with presentation of an alternative that works better. One way to better understand these principles is to apply them to common teaching situations. Some examples are presented in this month’s column.