SOLO Taxonomy

framework · education · organizing-schema

Biggs' Structure of the Observed Learning Outcome from prestructural to extended abstract.

The SOLO Taxonomy (Structure of the Observed Learning Outcome) was developed by John Biggs and Kevin Collis at the University of Newcastle (Australia) and presented in their 1982 Evaluating the Quality of Learning: The SOLO Taxonomy. Unlike Bloom's Taxonomy, which classifies cognitive processes by type, SOLO classifies the structural complexity of learning outcomes themselves through five levels: Prestructural (the student misses the point or shows minimal understanding); Unistructural (focuses on a single relevant aspect); Multistructural (focuses on several relevant aspects but treats them as separate); Relational (integrates aspects into a coherent whole); and Extended Abstract (generalizes the structure to new domains, abstracts to higher-level principles, makes connections beyond the original frame). The model's distinctive contribution is treating learning quality as a question of structural complexity in the student's understanding — visible in how the student organizes and relates information — rather than as cognitive-process type. SOLO has been particularly influential in higher-education assessment and outcomes-based curriculum design, including substantial use in Australia, New Zealand, and the UK. Pam Hook's subsequent application to K-12 classroom practice through HookED has substantially extended SOLO's reach. The framework pairs naturally with constructive alignment (Biggs's broader curriculum-design framework, in which intended outcomes, teaching activities, and assessment are deliberately aligned).

Originators

John Biggs; Kevin Collis high

Year / Decade

1982 (foundational publication); 2003 (Biggs's Teaching for Quality Learning at University with SOLO and constructive alignment) high

Primary sources

Biggs, J.B. & Collis, K.F. (1982). Evaluating the Quality of Learning: The SOLO Taxonomy, Biggs, J.B. & Tang, C. (2011). Teaching for Quality Learning at University (4th ed.) high

Core components

Five levels of structural complexity: Prestructural, Unistructural, Multistructural, Relational, Extended Abstract
Quantitative phase (uni-/multi-structural) and Qualitative phase (relational/extended abstract)
Focus on outcome structure rather than process type
Distinction from Bloom's process-typology approach
Connection to Biggs's constructive alignment
Application in higher-education outcomes assessment
Pam Hook's K-12 extension through HookED

Primary use case

Higher-education curriculum design and outcomes assessment; alternative or complement to Bloom's Taxonomy in objective specification; student self-assessment of understanding depth; teacher professional development; basis for outcomes-based education in Australia, New Zealand, UK; integration with constructive alignment for course design.

Common criticisms

Less widely adopted than Bloom's Taxonomy globally — particularly absent from US education contexts
classification of student responses can be subjective, with different graders coding the same response at different levels
the five-level structure may be too coarse for some assessment purposes and too fine for others
Extended Abstract level is rarely demonstrated in practice and may be aspirational
commercial branded extensions (HookED) vary in quality
like all hierarchical taxonomies, can become bureaucratic compliance with checklist application rather than substantive understanding of student work
works better in some disciplines (essay-based) than others (mathematical proof, code, performance arts).

Lineage

Siblings: Bloom's Taxonomy, Revised Bloom's Taxonomy, Webb's Depth of Knowledge