The SOLO Taxonomy

The SOLO Taxonomy is based on the study of outcomes of academic teaching. SOLO is short for “Structure of the Observed Learning Outcome” and the taxonomy names and distinguishes five different levels according to the cognitive processes required to obtain them: “SOLO describes a hierarchy where each partial construction [level] becomes a foundation on which further learning is built” (Biggs, 2003, p. 41). SOLO can be used to define ILOs, forms of teaching that support them, and forms of assessment that evaluate to what extent the ILOs were achieved. It is developed aiming at research-based university teaching as the research activities behind it ultimately converge on real research (i.e. on the production of new knowledge) at its fifth and highest level. The five levels are as follows, in increasing order of structural complexity (Biggs & Collis, 1982, pp. 17-31; Biggs, 2003, pp. 34-53; Biggs & Tang, 2007, pp. 76-80):

SOLO 1: “The Pre-Structural Level”

Here the student does not have any kind of understanding but uses irrelevant information and/or misses the point altogether. Scattered pieces of information may have been acquired, but they are unorganized, unstructured, and essentially void of actual content or relation to a topic or problem.

SOLO 2: “The Uni-Structural Level”

The student can deal with one single aspect and make obvious connections. The student can use terminology, recite (remember things), perform simple instructions/algorithms, paraphrase, identify, name, count, etc.

SOLO 3: “The Multi-Structural Level”

At this level the student can deal with several aspects but these are considered independently and not in connection. Metaphorically speaking; the student sees the many trees, but not the forest. He is able to enumerate, describe, classify, combine, apply methods, structure, execute procedures, etc.

SOLO 4: “The Relational Level”

At level four, the student may understand relations between several aspects and how they might fit together to form a whole. The understanding forms a structure and now he does see how the many trees form a forest. A student may thus have the competence to compare, relate, analyze, apply theory, explain in terms of cause and effect, etc.

SOLO 5: “The Extended Abstract Level”

At this level, which is the highest, a student may generalize structure beyond what was given, may perceive structure from many different perspectives, and transfer ideas to new areas. He may have the competence to generalize, hypothesize, criticize, theorize, etc. We define competence progression as moving up the SOLO levels; i.e. SOLO-progression. Surface learning (which has similarities to instrumental understanding) implies that the student is confined to action at the lower SOLO levels (2-3); whereas deep learning (which has similarities to relational understanding) implies that the student can act at any SOLO level (2-5), including the higher levels (4-5). As we move up the SOLO hierarchy, we first see quantitative improvements as the student becomes able to deal with first a single aspect (from 1-2) and then more aspects (from 2-3). Later we see qualitative improvements (from 3-4) as the details integrate to form a structure; and (from 4- 5) as the structure is generalized and the student can deal with information that was not given. For these reasons, the levels 2 and 3 are sometimes referred to as quantitative levels; levels 4 and 5 as the qualitative.