What is SOLO taxonomy?

SOLO (structure of observed learning outcomes) taxonomy is an illustrated model of learning that classifies depth of understanding into categories.

According to these categories, students could understand: nothing; something; several relevant things; several relevant things that they see relate to each other; or a few related things they can apply in new situations about any topic.

There are names for each of those levels of understanding: prestructural; unistructural; multistructural; relational; and extended abstract.

Importantly, there are symbols to represent each level too. For example, you can represent the unistructural level with a single line, and the multistructural level with three lines. Then, sketch the symbol for relational level with three lines, but joined to each other.

The symbols represent how each level builds on the previous. You can’t jump to understanding something relationally until you understand it multistructurally – you can’t draw three lines joined together until you’ve drawn three lines.

Why is it useful?

Teachers and students use this tool together. Students can categorise their own understanding in this taxonomy, or the difficulty of a lesson or question. They can see what they need to do to understand the topic at the next level. And they can appreciate why they need to learn apparently disparate facts – only when they’ve done that can they link them all together in the next lesson.

Using SOLO taxonomy involves learners in their own differentiation and makes the process behind learning explicit. It highlights the difference between surface and deep understanding, helping students understand where they are on that spectrum, and what they need to do to progress.

Students become aware of the reasons for everything they do and realise improvements are due to their own strategies rather than luck or fixed ability.

What does it look like in chemistry lessons?

‘Say you are teaching separation techniques,’ suggests Euan Douglas, head of science at Saint George Catholic College in Southampton. ‘Before a lesson on distillation or crystallisation, I’d tell my students that today’s lesson is at the multistructural level, or the “three bars” level – they don’t need to know the technical terms. My chart of SOLO taxonomy symbols is on the wall next to my board all the time so I can point to it.’

‘After learning about all the separation techniques, I’d tell them I’m going to ask them to use what they learn to make decisions about the best technique to use for different situations and mixtures, and that will be a lesson at the next level on the chart, and I’d point to the joined-up bars symbol. Then they know they’re aiming for understanding the techniques and linking them, not just recalling the facts.’

In your class

Download a SOLO taxonomy diagram to use with your class (MS Word or pdf).

How can I get started using it?

First time SOLO users can familiarise students with the symbols by setting a challenging question and asking students to match their own answers to one of the symbols representing levels of understanding, recommends Euan. ‘Students understand it almost instantly.’ Further practice could take the form of peer assessment – students assign each other’s work a symbol. ‘That’s about the most accurate peer assessment you can get,’ says Euan. ‘It stops them always just saying, “it was nice but you needed to write more”. With SOLO, they don’t need to write lengthy feedback and the next steps toward improvement are clear.’

Euan recommends two other ways SOLO could be useful:

Help students tackle the hardest exam questions

If a question looks too hard to complete, students tend to leave it blank rather than attempting a partial answer. Practice with SOLO can help students categorise levels of question difficulty. They get to recognise phrases like ‘explain why’ in questions mean it requires an answer at an extended abstract level, and are less surprised it’s hard to answer. If they can’t answer at that level, they can alter the command word of the question to make it a multistructural-level question about the same topic and have a go at that.

It also helps students structure longer answers – they can see why their first sentence should be at a unistructural level. You must state something relevant first before explaining how it relates to something else. They get into the habit of starting at the basics and working up logically.

Motivate students to learn independently

Explicitly explaining why your students need to, say, watch a video of a practical before coming to the lesson to carry it out can mean they’re more likely to do it. Tell them you don’t have time in the lesson to get them through the unistructural level (knowing the equipment) and the multistructural level (using that apparatus to learn about accuracy of readings). Explain it’s better to spend time on just the more complex multistructural stage together. In other words, this is making the reasons for flipped learning plain to students using SOLO taxonomy.

What can’t I use SOLO for?

Attempting to match SOLO levels to predicted grades isn’t its best use in chemistry. It’s better to apply the taxonomy to more specific situations, like individual questions or lessons, to help students see how new knowledge builds on past learning.