Ironically, however, many schools today bear Maria Montessori's name while only loosely adhering to her methods. This is because the word is not trademarked. While there are official Montessori institutions in different countries providing teacher training and accreditation, this is not necessary for schools to use the term in their advertising.
"It is increasingly difficult to find authentic Montessori education," says L'Ecuyer, who worries that some schools may simply be following a trend, without truly embracing the principles regarding child autonomy, or the length of the learning sessions – all of which could influence important outcomes. The lack of consistency in applying the method may explain why there is variability in measures of the Montessori method's benefits, including some failures to note any advantages over other educational systems.
Marshall is more sanguine about these changes. While she agrees that the diverse approaches can sometimes skew assessments of the Montessori method, she also recognises that the movement may need to adapt to social and technological change. Take electronic devices, and their many uses in education: "That's not something she could have written about."