The document discusses the theories of several prominent developmental psychologists and educators regarding the importance of using manipulatives in mathematics education. It explains that according to Bruner, Piaget, Vygotsky, Dienes, and Kamii, manipulatives are essential for helping children connect abstract mathematical concepts to concrete experiences and for constructing logico-mathematical knowledge from interaction with their environment. The document advocates for introducing math concepts to young children through hands-on games and activities rather than a purely abstract approach.