SOLO Taxonomy

SOLO Taxonomy


SOLO Taxonomy is a systematic way of describing how a learner’s understanding develops from simple to complex when learning different subjects or tasks.

The SOLO stands for:

Structure of Observed Learning Outcomes


Alternative to Bloom’s Taxonomy

The SOLO Taxonomy (Structure of Observed Learning Outcomes) was devised by Biggs and Collis in 1982 as an alternative to Bloom’s (Cognitive Domain) Taxonomy. Bloom’s Taxonomy has been used for several decades to develop learning and teaching strategies. Bloom’s categorizes learning from simply remembering to more complex cognitive structures such as analyzing and evaluating.


Structure of the Observed Learning Outcomes

Through their work, Biggs and Collis looked at the Structure of the Observed Learning Outcomes produced by learners in terms of complexity. Their model describes levels of increasing complexity in a learner’s understanding of subjects or performance tasks.

The SOLO Taxonomy is divided into five levels of understanding. It is hierarchal and each stage involves the previous and adds something to it.


Uses for SOLO Taxonomy

  • to increase quality and complexity of thought
  • to set learning objectives
  • to define learning outcomes
  • to created assessment criteria
  • to create and evaluate learning programs


SOLO Taxonomy


Five Hierarchical Levels of Understanding

The SOLO model consists of the following five hierarchical levels of understanding that range from incompetence to expertise.

  1. Prestructural:  Incompetent – nothing known about the subject or task
  2. Unistructural:  One relevant aspect is known
  3. Multistructural:  Several relevant independent aspects are known
  4. Relational:  Aspects of knowledge are integrated into a structure
  5. Extended Abstract:  Knowledge is generalized into a new domain


SOLO Taxonomy Diagram




Levels of Understanding Explained


At this level, the learner is simply acquiring bits of unconnected information. It has no organization and does not make sense to them. The learner does not understood the information, therefore, cannot demonstrate understanding.

The learner’s response shows they have missed the point of the information.


At this level, the learner has only a basic concept about the subject or task. They are able to make simple and obvious connections, but the broader significance of the information is not understood.

The learner’s response demonstrates a concrete understanding of the topic, but it only focuses on one relevant aspect.



At this level, the learner can understand several aspects of the subject or task, but its relationship to each other and to the whole remains separated. Ideas and concepts around a topic are not connected. The learner can make a number of connections, but the significance of the whole is not understood.

The learner’s response focuses on some relevant aspects, but they are treated independently.



At this level, the learner is able to understand the significance of the parts in relation to the whole. Ideas and concepts are linked, and they provide a coherent understanding of the whole.

The learner’s response demonstrates an understanding of the topic by being able to join all the parts together. They are able to show how the parts contribute to the whole.


Extended Abstract

At this level, the learner is able to make connections not only within the given subject field, but also make connections beyond it. They are able to generalize and transfer the principles and concepts from one subject area into a new and different domain.

The learner’s response demonstrates they are able to conceptualize at a level that extends beyond what has been taught. They are able to create new ideas and concepts based on their understanding of the subject or task being taught.



Sample Verbs

The SOLO taxonomy lists verbs associated with learning outcomes at each level.

Level Verbs
Prestructural Failed, unsuccessful, flunked, Learner missed the point
Unistructural List, Name, Memorize, Define, Identify, Do a simple procedure
Multistructural Define, Describe, Classify, Combine, Do algorithms
Relational Analyze, Explain, Integrate, Sequence, Relate, Apply, Compare, Contrast
Extended Abstract Reflect, Evaluate, Theorize, Hypothesize, Generalize, Predict, Create, Imagine



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