Where does scaffolding collide?

Wood, Bruner, and Ross coined scaffolding in their 1976 tutoring study to name the temporary, calibrated support that lets a learner carry out a task beyond present reach: the tutor controls the parts the child cannot yet manage and removes that control, or fades it, as competence grows. The metaphor rests on Vygotsky's zone of proximal development, the distance between what a learner can do alone and what the same learner can do with guidance. The defining property is impermanence. Support that is never withdrawn is, by Wood, Bruner, and Ross's account, not scaffolding but dependence.[1][2]

Unit

A learner within a supported task

Recovery means

Faded deliberately: support is withdrawn in steps as the learner takes over the task

Measured by

Observation and coding of contingent tutor moves; performance and transfer once the support is removed

Reiser carried the term into technology-supported learning in 2004 and split its function into two mechanisms: structuring, which reduces the complexity of a task, and problematizing, which makes selected features harder so that learners must confront them. In this literature the support is often built into a tool or a printed prompt rather than supplied by a person, which raises the distinction between hard scaffolds, fixed in advance, and soft scaffolds, adjusted on the fly, and the question of who or what does the fading when no tutor is present. The construct keeps Wood, Bruner, and Ross's logic of temporary, calibrated support and relocates it from the tutor to the designed environment.[3]

Unit

A learner within a designed task or tool

Recovery means

Faded by design: prompts are removed or thinned as the task is repeated

Measured by

Analysis of the designed supports; learning and transfer with and without the scaffold present

In tissue engineering a scaffold is a three-dimensional biomaterial structure onto which cells attach, proliferate, and organize into new tissue. Langer and Vacanti named the field in 1993 and placed the scaffold at its center: a porous matrix, natural or synthetic, that supplies the mechanical template and surface a growing tissue needs. Hollister's 2005 account treats scaffold design as an engineering problem of porosity, stiffness, and degradation rate. The word reached this field from construction, not from Wood, Bruner, and Ross, and the referent is a physical object, present rather than withdrawn, even where the polymer is engineered to resorb as tissue replaces it.[4][5]

Unit

An engineered biomaterial structure

Recovery means

Not applicable: a physical structure, though degradable scaffolds resorb as tissue forms

Measured by

Characterization of porosity, mechanical properties, and degradation; cell and tissue response in vitro and in vivo

In medicinal chemistry a scaffold, or molecular framework, is the core ring system together with the linkers joining it, the part of a molecule that remains when side chains are removed. Bemis and Murcko formalized the definition in 1996 by reducing known drugs to their frameworks and showing how few distinct shapes account for most compounds. Chemists design a series around a fixed scaffold and vary the substituents, and speak of scaffold hopping when they seek a new core with the same activity. The referent is neither a support nor a growth template but a shared substructure: the word marks what a set of molecules have in common.[6]

Unit

The core substructure of a molecule or compound series

Recovery means

Not applicable: a structural feature of a molecule

Measured by

Framework extraction from molecular graphs; scaffold diversity and frequency analyses