She used the term "valorization" to describe the adolescents' drive for an externally derived evaluation of their worth.
The third plane of development extends from around twelve years to around eighteen years of age, encompassing the period of adolescence. Montessori characterized the third plane by the physical changes of puberty and adolescence, but also psychological changes. She emphasized the psychological instability and difficulties in the concentration of this age, as well as the creative tendencies and the development of "a sense of justice and a sense of personal dignity". She used the term "valorization" to describe the adolescents' drive for an externally derived evaluation of their worth. Developmentally, Montessori believed that the work of the third plane child is the construction of the adult self in society.[40]