When introducing vocabulary to the child, Montessori teachers use specific language in a specific order to help introduce, practice and check for mastery. This is called the Three Period Lesson. The lesson can be used throughout the Montessori Environment. The lesson is used to increase and enrich the child’s vocabulary. Edouard Seguin, a French physician who worked with special needs children during the late 19th century, was an influence on Maria Montessori in many ways.

“Sensitive Periods” is a term used in Montessori education. The term was originally coined by the scientist Hugo de Vries (a botanist) and connected the research by scientist Jacques Loeb (physiologist and biologist). Loeb studied butterflies and noticed that the larvae needed very specific leaves located at the top of the trees. They have a period of time when they are more attracted to light so they naturally climb towards the top of the trees and then eat those leaves.