At the same time, it was concluded that while some evidence exists that children may benefit cognitively and socially from Montessori education that sticks to original principles, it is less clear whether modern adapted forms of Montessori education are as effective.[
A 2017 review on evaluations of Montessori education studies states that broad evidence exists that certain elements of the Montessori method (e.g. teaching early literacy through a phonics approach embedded in a rich language context, providing a sensorial foundation for mathematics education) are effective, although these studies suffer from several methodological limitations. At the same time, it was concluded that while some evidence exists that children may benefit cognitively and socially from Montessori education that sticks to original principles, it is less clear whether modern adapted forms of Montessori education are as effective.[7] In 2017, Lillard also reviewed research on the outcomes of Montessori education.[43]