The concept was first introduced by Wood, Bruner, and Ross (1976) for investigating the help that an adult gives to an individual learner to perform a task that is too difficult for a child to accomplish alone. According to them, scaffolding included such elements as arousing the learner’s interest in the task; reducing the degrees of freedom - and hence the complexity of problem space - in the task to suit the learner’s level of expertise; directing the learner’s activity towards the task goals; highlighting the critical features of the task; helping to control frustration; and modeling the solution to a task.
Wood, D., Bruner, J. S., & Ross, G. (1976). The role of tutoring in problem solving. Journal of Child Psychology and Psychiatry, 17, 89-100.