SOLO Taxonomy: Five Levels of Understanding Explained

SOLO Taxonomy: Five Levels of Understanding Explained is a teacher guide to the Structure of Observed Learning Outcomes. John Biggs and Kevin Collis developed this assessment framework. It describes the quality of a learner's response, from no relevant understanding to abstract reasoning that they can transfer to new tasks (Biggs & Collis, 1982).

SOLO Taxonomy is short for Structure of Observed Learning Outcome. John Biggs and Kevin Collis (1982) developed it as an educational assessment framework. Teachers use it to classify the quality and complexity of observable learner responses across five SOLO levels: prestructural, unistructural, multistructural, relational and extended abstract.

For a busy teacher, its value is diagnostic: it helps separate a demanding task from the response a learner actually gives. In a Year 8 science lesson on evaporation, one learner may name heat as a factor, another may list heat, surface area and airflow, while a third explains how those factors interact and predicts what would happen in a new context.

What SOLO Taxonomy Means

John Biggs and Kevin Collis (1982) developed SOLO Taxonomy, or the Structure of Observed Learning Outcome. It classifies five levels of observable learner understanding. These are prestructural, unistructural, multistructural, relational, and extended abstract. Teachers use SOLO to check learner understanding, help learners connect facts and create new ideas.

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For a broader view of how this fits alongside other classroom methods, see our guide to evidence-based pedagogy.

Biggs and Collis (1982) created the SOLO taxonomy. It uses five levels to check the quality of learner answers.

These levels are prestructural, unistructural, multistructural, relational, and extended abstract. Unlike Bloom's (1956) taxonomy, SOLO focuses on how learners respond. It helps with formative assessment, so teachers can see what to teach next.

Biggs and Collis (1982) created SOLO Taxonomy to assess learner understanding. It shows five levels, from basic recall to complex application. Teachers use this framework to build learners' thinking skills. They can also plan activities with SOLO Taxonomy (Hattie, 2012).

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Biggs and Collis created SOLO Taxonomy to describe the structure of observed learning outcomes. The framework helps teachers see the quality of learner understanding and plan suitable next steps (Biggs & Collis, 1982).

Constructive alignment means matching learning aims, activities, and assessments. Biggs (2003) says this improves learning. When these areas fit together, learners are more likely to build understanding, as suggested by Hattie (2009) and Marzano (2000).

SOLO Taxonomy helps teachers understand what learners know (Biggs & Collis, 1982). Teachers can then give targeted feedback that supports learner progress (Hattie & Timperley, 2007).

This framework also supports critical thinking, such as analysis (Bloom, 1956). Teachers can use it to personalise learning, so each learner can reach their potential (Vygotsky, 1978).

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Why Teachers Use SOLO Taxonomy

SOLO Taxonomy aids learner progress. It shows learners their current understanding level and next steps. Teachers use SOLO levels to plan lessons matching each learner’s knowledge, helping them move from isolated ideas towards connected and extended understanding (Biggs & Collis, 1982; Hook & Mills, 2011).

Damopolii (2020) shows how learners build understanding through SOLO Taxonomy. Teachers use it to support learning and comprehension, which means clear understanding. Scaffolding and ZPD help learners make similar progress.

SOLO Taxonomy is a valuable tool for assessing the structure and quality of understanding that learners show in a particular subject or task. It allows teachers to identify where learners are in their learning process and determine what steps need to be taken to move them to a deeper level of understanding (Biggs & Collis, 1982).

SOLO Taxonomy lets teachers plan lessons matched to each learner's understanding. It helps them gain deeper knowledge. This is like differentiation and makes learning better (Biggs & Collis, 1982). Learners engage more, improving their results (Hattie, 2008).

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The Origins of SOLO Taxonomy: Biggs and Collis (1982)

Biggs and Collis published SOLO Taxonomy in 1982, influenced by Piaget's (1952) account of cognitive development. They found learners' task responses changed structurally, not just in number (Biggs & Collis, 1982). Learners moved from fragmented ideas to abstract understanding. SOLO focuses on thinking structure, unlike earlier taxonomies that looked at knowledge content.

SOLO (Structure of Observed Learning Outcome) matters because it focuses on what learners produce. Biggs and Collis (1982) linked SOLO to observable learner work. This helps teachers assess written work, explanations, or demonstrations.

SOLO is more practical than frameworks based on thinking teachers cannot see. Piaget's stages showed limits, but SOLO shows levels within a task. A learner can be relational in geography, but unistructural in maths (Biggs, 1999).

Biggs and Tang (2011) link SOLO taxonomy with constructive alignment. In simple terms, this means matching learning outcomes, activities, and assessments to SOLO levels.

For example, explaining climate change needs relational tasks, where learners connect ideas. This alignment shows learners the depth of understanding they need. It may improve learner achievement and awareness.

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The Five SOLO Levels Explained

Biggs and Collis (1982) created SOLO Taxonomy to show different levels of learner thinking. Teachers can use it to check learner understanding effectively. The taxonomy has five levels. Each level shows a specific depth of what the learner knows.

1. Prestructural Level: Here, learners exhibit a lack of understanding, often missing the point entirely. The level of thinking is minimal, with a focus more on lower-order verbs such as identify, memorise, and recall. This limited processing may be due to cognitive load overwhelming the student's working memory. It's the first stepping stone, a difficulty level that needs overcoming before progressing.
2. Unistructural Level: At this stage, learners can identify singular aspects of knowledge, and their understanding is limited to isolated disciplinary knowledge. For instance, a learner can identify that water boils at 100 degrees Celsius but may not understand why this happens. This level shows the beginning of schema formation.
3. Multistructural Level: The quantity of knowledge increases at this level. learners begin to gather multiple pieces of information, but they struggle to relate them coherently. For example, a learner in this stage can know the boiling point of water and that heat energy is involved, yet fail to link these facts.
4. Relational Level: This is where the magic of student-led learning starts to manifest. learners begin to connect the multistructural elements into a coherent whole. Their level of thinking becomes more complex, and they start to understand the relationships between facts. This connects well with inquiry-based learning approaches and classroom dialogue. For instance, a learner at this level would understand that water boils at 100 degrees Celsius due to the increased kinetic energy of water molecules.
5. Extended Abstract Level: The zenith of understanding, where learners can generalise beyond the given context and apply their knowledge to new, abstract situations. At this level, learners demonstrate the highest quality of learning, showing creative and effective thinking. They can take their relational understanding and extend it to hypothetical scenarios or different contexts entirely. For example, a learner can understand not only why water boils at 100 degrees Celsius but also predict how altitude or atmospheric pressure would affect this process, or apply these principles to other substances.

Each level builds upon the previous one, creating a progression that teachers can use to design learning activities and assess learner understanding (Biggs & Collis, 1982). The value of SOLO Taxonomy lies in its ability to show what learners know and how they can use that knowledge to think and reason.

This detailed understanding lets teachers pinpoint a learner's progress. It helps teachers plan support to aid learner development. SOLO Taxonomy shows thinking quality, unlike simple right or wrong marking (Biggs & Collis, 1982). This moves beyond traditional assessment.

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SOLO Taxonomy and Bloom's Taxonomy: Understanding the Difference

Teachers use SOLO and Bloom's Taxonomies for assessment design. To use them well, it helps to know how they differ.

Bloom's Revised Taxonomy (Anderson & Krathwohl, 2001) has six categories that show learner thinking. SOLO Taxonomy (Hattie & Purdie, 1998) shows the quality of a learner's response, not just their thinking. A learner at Multistructural level applies knowledge step by step (Hattie & Purdie, 1998).

For planning, Bloom's Taxonomy helps teachers map curricula (Biggs & Tang, 2011). Its categories help teachers state the cognitive challenge in learning aims. Does the unit ask learners to recall, or evaluate and create?

SOLO Taxonomy better suits in-lesson checks because it shows the quality of a learner's response. If a learner lists facts without links, teachers know it's Multistructural. A "How do these ideas connect?" question prompts better thinking (Biggs & Tang, 2011).

Teachers often find Bloom's and SOLO Taxonomies work well together. Use Bloom's Taxonomy to plan learning objectives and schemes of work. SOLO Taxonomy helps teachers design lesson questions and rubrics.

Biggs and Tang (2011) suggest writing SOLO learning outcomes clearly. Choose activities that show the required SOLO level. Bloom's and SOLO languages work together because they describe different aspects of learning.

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SOLO Taxonomy Classroom Implementation Guide

SOLO Taxonomy helps teachers design learning. Use the five levels from Biggs and Collis (1982) for activities and feedback. First, identify the target SOLO level. Use it as a starting point for professional discussion: identify the learner's current need, record evidence from more than one lesson, and agree the next classroom adjustment with the SENCO or family.

Then, design activities that help learners progress. Use SOLO questions and rubrics to check understanding.

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Use SOLO Taxonomy to plan lessons. Start with activities where learners grasp one idea (unistructural).

Next, use tasks where learners work with several facts (multistructural). Biggs and Collis (1982) suggest retrieval practice for basic levels. For higher levels, they advise problem solving.

SOLO levels can make digital assessment more useful. This works best when teachers treat AI and automated marking as a prompt for professional judgement. In an AI-assisted classroom, extended abstract writing can be generated quickly. So teachers should also assess the live cognitive process: oral explanation, draft history, worked examples and how learners respond to probing questions (Bearman et al., 2023).

SOLO rubrics change how you teach and how learners learn. These rubrics clearly state expectations (Biggs & Collis, 1982). Teachers gain a structured way to check learner progress.

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Learners use this approach to self-assess and to understand deeper thinking (Hattie & Timperley, 2007). It builds metacognition, which means thinking about and guiding your own learning. This includes monitoring and executive control, as described by Brown (1987) and Flavell (1979).

Questioning should mirror SOLO levels. Teachers can plan questions building cognitive demand, from recall to abstract thought (Biggs & Collis, 1982). This helps every learner gain deeper understanding and face suitable challenges (Bloom, 1956).

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SOLO Taxonomy Verbs: Designing Questions and Tasks at Each Level

Biggs and Collis (1982) linked verbs to SOLO levels. Use these verbs in questions and tasks. Matching verbs to SOLO levels aligns tasks to learning. This helps learners understand expected responses, clarifying rubrics.

At the Prestructural level, verbs such as misidentify, tautologise, and miss the point describe the response a learner gives. This helps teachers diagnose a starting point, but it is not a useful task verb. Teachers use this level as a baseline, not as a target.

At the Unistructural level, useful task verbs include identify, name, define, follow a simple procedure, and recall one relevant fact. A history teacher can ask: "Name one cause of the First World War." At the Multistructural level, verbs shift to describe, list, enumerate, classify, and outline several features. The same teacher can ask: "Describe three causes of the First World War", which needs more information but does not yet ask learners to link the causes into a clear explanation (Hook & Mills, 2011).

At the Relational level, learners explain, compare, and analyse (Hook & Mills, 2011). They bring information together so they can explain links.

At the Extended Abstract level, activities ask learners to theorise and evaluate (Hook & Mills, 2011). Teachers can use these verb levels to build reasoning skills and help learners see their next steps (Hook & Mills, 2011).

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SOLO Taxonomy Assessment Strategies

SOLO Taxonomy helps teachers view learner understanding (Biggs & Collis, 1982). It moves beyond basic tests to check how learners think. This helps teachers plan better lessons. The five levels guide teachers and learners toward deeper knowledge (Biggs & Collis, 1982).

SOLO Taxonomy helps teachers assess learning and adapt their teaching. When teachers design lessons with SOLO levels, they build learner thinking (Biggs & Collis, 1982). This helps learners develop cognitive skills, not just memorise facts. They gain real understanding and apply knowledge creatively (Biggs & Tang, 2007).

SOLO Taxonomy helps learners think critically. Teachers can use it to support deeper learning, said Biggs & Collis (1982). Frameworks help learners remember and use knowledge. This boosts results, according to Biggs & Tang (2011).

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Criticisms and Limitations of SOLO Taxonomy

SOLO Taxonomy is popular, but teachers need to know its limits. Hattie and Purdie (1998) find linearity a key issue, because the model assumes learners move through five levels in order.

In practice, learners may show Extended Abstract thought early. This can happen before they have Unistructural knowledge. They can also copy Relational writing without genuine understanding.

Biggs and Collis (1982) found SOLO levels differ across subjects. Extended Abstract thinking varies in maths and English. Critics say the framework is too generic (Marzano & Kendall, 2007). Teachers need subject-specific examples for reliable learner assessment.

Culture and language affect learning. Watkins and Biggs (2001) noted SOLO is not always easy to use in East Asia.

Some learners show understanding in different ways, so SOLO may mark them down. SOLO is useful, but its scores do not show everything.

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Frequently Asked Questions

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Implementation Time in the Classroom

Teachers can use basic SOLO Taxonomy quickly (Biggs & Collis, 1982). Apply the five levels to one lesson area first. Expand to other subjects after a term for confident results.

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SOLO Taxonomy in primary classrooms

SOLO Taxonomy works for primary learners if you use simple language and pictures. Young learners grasp "one idea" versus "linking ideas" with colours or symbols. It helps you scaffold learning and see where each learner needs help.

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SOLO Taxonomy and Bloom's Taxonomy for lesson planning

SOLO Taxonomy tracks the structure of learner answers, while Bloom's stresses thinking skills (Bloom, 1956). Teachers use SOLO to design questions that show learners' ability to link ideas. SOLO feels more useful for daily marking, as it reveals learner understanding (Biggs & Collis, 1982).

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SOLO Taxonomy rubrics for different subjects

Identify your subject's core concept and abstract versions of it. History learners, for example, move from facts to cause and effect explanations. Offer subject-specific examples for each learning level. (Bloom, 1956) (Krathwohl, 2002)

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Is SOLO Taxonomy suitable for learners with special educational needs?

SOLO Taxonomy can support learners with SEN. It shows small steps in progress and values different levels of understanding.

Teachers can use the framework to set realistic goals. They can also recognise achievement at every level (Biggs & Collis, 1982). Visuals help learners understand abstract concepts (Hattie, 2009).

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Free Resource Pack

Download this free Thinking Framework (Green/Orange/Blue/Red) resource pack for your classroom and staff room. Includes printable posters, desk cards, and CPD materials. Use it as a starting point for professional discussion: identify the learner's current need, record evidence from more than one lesson, and agree the next classroom adjustment with the SENCO or family.

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