During World War II, Montessori schools in Europe were closed due to fascist expansion. In 1940, when India also joined World War II, Dr. Montessori and her son Mario Montessori were regarded as foreign enemies, but she was still allowed to carry out training courses. They have been in India until the 1940s. In those years, she lived in an Indian family, which gave her the opportunity to observe the child's birth-adult stage and improve her understanding of children in primary school and adolescence (ages 12-18).
After returning from India, Dr. Montessori collaborated with Adele Costa Gnocchi to study the needs of children under three years of age, and finally published "The Absorbent Mind" (1949). In view of her educational work injecting new ideas into the world and expanding the world's understanding, Dr. Montessori was nominated for the Nobel Peace Prize three times in 1949, 1950 and 1951 respectively.