The SOLO taxonomy
The theoretical background of the SOLO taxonomy
SOLO stands for Structure of the Observed Learning Outcome. The SOLO Taxonomy is the brainchild of Biggs and Collis (1982). Its essence, application and alignment with the curriculum is detailed in Biggs (1995, 1999a, 1999b). According to the SOLO taxonomy, the assessment of learners' performance is based on their development in terms of the complexity in understanding, from surface understanding to deep understanding. Thus, five stages of development are identified:
1. pre-structural,
2. unistructural,
3. multi-structural,
4. relational, and
5. extended abstract.
The five stages are elaborated in the following way (Biggs, 1995, pp.11-12):
Pre-structural: The task is not attacked appropriately; the student hasn't really understood the point and uses too simple a way of going about it. The performance is incompetent.
Unistructural: One or a few aspects of the task are picked up and used. Verbs/Terms: identify, name. Learning goals include acquiring terminology, to accomplish the first step in mastering a task.
Multi-structural: Several aspects of the task are learned but are treated as if they were separate. Verbs/terms: combine, describe, list, how many ways can you... what are the main points... Learning goals require coverage, 'knowing about', performing algorithms such as the four rules of number.
Relational: The quantitative component aspects then become integrated into a coherent whole; this level is what is normally meant by an adequate understanding of the topic. However, there are many subgoals, which involve more or less understanding. Verbs/terms: analyze, criticize, argue, justify, understand, apply, relate X with Y, explain. Learning goals emphasize understanding, application, problem solving, conceptualizing, reasoning, and inquiring.
Extended abstract: The previous integrated whole may be conceptualized at a higher level of abstraction and generalized to a new topic or area. Verbs/terms: hypothesize, reflect, generate. Learning goals require students to theorize about a topic.
These five stages of development of understanding also reflect the cognitive complexity of learning. Accordingly, learners' performance is assessed along these dimensions.
Though most commonly cited with reference to assessment, the SOLO taxonomy in fact exerts its influence beyond assessment. It is a "potentially useful tool in higher education both to shape and assess learning" (Boulton-Lewis, 1995, p.152). The ultimate goal of the SOLO taxonomy is a teaching and learning system termed "constructive alignment" (Biggs, 1999a), which, in Biggs' own words, is a system, "from objectives through teaching to assessing the outcomes, is aligned on the basis of learning activities embedded in the objectives" (Biggs 2002, p.6).
For the SOLO taxonomy to be effective, the curriculum objectives must be explicitly stated and clearly spelled out to both teachers and learners. The teaching activities, including the assessment tasks and assessment criteria, must be designed with reference to the complexity of understanding consistent with the course objectives.
