Maximum effort is the conscious exertion of power or hard work on a job requiring time and effort—going beyond expectancy of effort. Montessori believed growth depended on the opportunity to expend maximum effort. (Boehnlein)

“… means expending much energy – psychic or other energy. Effort means to strive and to exercise one's faculties more than one thinks is within one's power to do – to go beyond one's strength. And when the child is unhampered in his activity, we see that he is ready to do, to accomplish, much more than we expect because it is through this intense mental exercise that he develops himself. And development is not a fatigue, nor is it inertia or rest. The vital activity of growth is continuous and never tires. …Therefore it is necessary that all past erroneous ideas be revized. We must give the children, the young, the possibility of development with maximum effort. The phenomenon of maximum effort is itself a manifestation which is a guide for the whole of education. Everywhere, in all its phases and during every moment of its duration, growth has a tendency to the maximum effort. (Note: Excerpt taken from Maria Montessori's last lecture for the Advanced Training Course on March 29th, 1944, Kodaikanal, India. Montessori, Maria, “Montessori to the Students of her Advanced Course” Communications, 1986, 2-3, pp. 38-39)