Discipline is the second pre requisite condition for learning. Montessori discipline is an "Inner Discipline" - an inner control which a child developes from his or her own behavior with the help of Montessori materials and in conjunction with his or her home environment. Dr. Montessori noted that many so called undisciplined children were really frustrated by lack of proper stimulation and an inadequate opportunity to achieve. She noted that young children become happier and more self controlled after a period of time in the Montessori class. She experienced challenging tasks which not only absorbed their energies, but resulted in a sense of achievement.