Singapore math was inspired largely by research from Jerome Bruner on how children learn. See https://singaporemathsclub.com/concrete-pictorial-and-abstract-ho

Singapore math was inspired largely by research from Jerome Bruner on how children learn. See https://singaporemathsclub.com/concrete-pictorial-and-abstract-how-one-psychologist-revolutionized-math-forever/ https://singaporemathsclub.com/concrete-pictorial-and-abstra... for more. His thinking at least parallels Marie Montessori's. There probably is some direct influence, but I couldn't find evidence of it in a quick search. However it does not surprise me that the approaches would work out to be similar.