 The MKO is typically assumed to be an older, more experienced teacher or parent, but often can be a learner's peer or someone their junior.The MKO need not even be a person, it can be a machine or book, or other source of visual and/or audio input.Elaborating on Vygotsky's theory, Jerome Bruner and other educational psychologists developed the important concept of instructional scaffolding, in which the social or information environment offers supports for learning that are gradually withdrawn as they become internalized.