To what extent is Didau's rejection of the SOLO Taxonomy convincing?

A response to this blog by David Didau in June 2014.

In it I will consider to what extent Didau’s rejection of the SOLO Taxonomy is convincing.

First, I will state Didau’s position.
  1. In October 2011, Didau wrote this blog regarding his early experiences of SOLO.  
  2. In January 2012, he wrote this blog regarding his delivery of SOLO Taxonomy training
  3. In May/June 2012 regarding the specific use of SOLO in Shakespeare and
  4. In June 2012 this blog regarding whether SOLO was a waste of time

In the blog of 2014 Didau explains how he thought his original experience of SOLO, and how it could be used to make learning and progress visible during the lesson, was nothing more than an assumption on his part. He also felt that the shared language of SOLO did nothing more than support an artificial and superficial indicator of progress. He then speaks about how time spent teaching the “cross-curricular language” could be much better spent “developing domain specific language that might be tailored to separated subject disciplines”. Didau claims that SOLO might be useful for teachers to effectively plan learning outcomes, especially regarding progressions. Having claimed that SOLO isn’t rubbish, just unnecessary, he moves on to describing the “cult” of SOLO Taxonomy practitioners who are “fleering (sic) and scorning on Twitter” should he “demure” (sic). Finally, he claims that practitioners who conclude that it is the best way to teach students shouldn’t be told that they are wrong. “But if you want to suggest that other teachers should be using SOLO, the burden of proof lies with you…Extraordinary claims, require extraordinary evidence” (ECREE)


To what extent, however, is this convincing? Didau has touched upon several valid criticisms of SOLO taxonomy, namely:
  • It can’t be used to evidence progress in each lesson
  • It is a general taxonomy that can’t be effectively applied to individual subject areas
  • Its extraordinary claims require extraordinary evidence  
What Didau appears to have overlooked is the original text regarding SOLO. This seems to be an action of his that isn’t unique. If we start with his final quote from Carl Sagan (ECREE). This is often used to discredit someone’s research. However, to do so correctly requires understanding of the original work from Hume’s essay “On Miracles”. Hume explains what an “Extraordinary claim” is: something that is contradicted by a massive amount of research evidence. Is there a large body of research evidence that claims that SOLO doesn’t work? No there isn’t. We only have one practitioners experience to consider here. And much of what displeases Didau isn’t based on anyone’s claims, but on his own assumptions. Maybe Didau expected SOLO to be miraculous in its application?

At the time of his first SOLO blogs, there was an expectation that teachers should demonstrate progress in every lesson. To his credit, Didau tried to help a profession to meet this expectation by finding a way to give everyone the chance to experience progress. This, however, was never a claim of SOLO. The original SOLO work was published by Biggs and Collis in 1982 (“Evaluating the quality of learning: The SOLO taxonomy), about 30 years before the focus on progress was declared by OfSTED. So Didau was pinning his hopes where they were never declared to exist by the original authors.

And finally, he claims that SOLO is a general taxonomy that can’t be applied effectively to individual subject areas. Here we see the difference between a Secondary and Primary practitioner. In Primary, the general rules apply; in Secondary the specific takes priority. What is an effective learning process for numeracy is also relevant to, and effective for, e.g. literacy. In fact, in my experience, SOLO can be effectively applied in all subject areas to support learning. Even more than this, the development of SOLO came from all subject areas.


Imagine giving an open-ended challenge to several students working individually: “Discuss Oliver Cromwell”. After a while, you collect their responses. Then you categorise them based on their outcomes. From here you start to see the Structure of Observed Learning Outcomes. Some responders will have no idea about him (Pre-Structural). Some will have a limited amount of knowledge (Uni-Structural). Some will have even more correct knowledge of him but aren’t yet making connections between the knowledge (Multi-Structural). These parts of the structure represent surface learning and look at how much people know.

Now we move toward deep learning. Not how much they know but how well that know it. From Quantity to Quality. The responses look at the connections between their knowledge. Students can describe the schema that is developing in their minds. We are now at the Relational part of the SOLO structure. And finally, there is the extended abstract. This is where students start conjecturing and hypothesising. Maybe they consider what would have happened had Cromwell met a premature end before the death of King Charles I.

So, the structure is defined in History. Biggs and Collis now look at other subject areas. In fact, they look at all available subjects at that time. And they discover that the structure is true in all subject areas. If this is the structure, and we aren’t explicitly teaching students to achieve these levels, it is possible that SOLO is an integral and organic representation of how we learn. This, therefore, demonstrates that SOLO, having been developed from all subject areas, is applicable to all subject areas. Didau is right when he says that a generic lesson regarding SOLO is less effective that teaching about it in the context of a subject. But to claim that it can’t be applied equally to individual subjects is against its formation.

What Didau has in fact presented is a denial of the SOLO Taxonomy, rather than a refutation. He has dismissed it by simply stating that it hasn’t worked for him; he hasn’t attempted to criticise its foundations. We see his blog as an acknowledgement of an implementation problem. As such, his position that SOLO is no longer worth spending any time on is untenable.

Where his rejection fails is regarding his evidence that SOLO hasn’t worked for him and his students. This is based on no more than, not a Student Voice, but a Student Silence. In his blog, Didau claims that the removal of displays elicited from his students not one comment that they “missed it”. Yet he claims that he continued to think about the structure of SOLO long after he’d stopped referring to. Perhaps his students did the same? That they didn’t voice it does not prove that they didn’t think about it. There is also an air of tension within the blog. On one hand Didau says “Much of the time I had invested into teaching the taxonomy was based on the flawed belief that it would help students demonstrate progress” followed immediately by “And make no mistake, it is great for getting students to demonstrate progress; but of what?” And then “…I continued to find it useful to refer to SOLO levels to help me think about progression…”. So, it’s not clear from Didau if SOLO does or doesn’t support progress.

It does seem that SOLO fell short of Didau’s own inflated hopes of how it could ultimately please OfSTED. At the time of his first blogs, he had moved to a new school and OfSTED were reputedly looking for evidence of progress being made in every lesson. What better than a superficial structure amongst which students could readily move based on their responses to differentiated tasks set by the teacher? This short termism is often confused with a miraculous claim. The eternal quest for a silver bullet. And it is here that we should consider the language of, and actions within, his blog:

  • Revelation
  • Convert
  • Cult
  • Miracle (ECREE)

The invocation of religion makes his actions seem like Henry VIII during the Dissolution of the Monasteries.


Didau talks about removing displays in the classroom (destruction of iconography)

He has removed from his website resources that promote SOLO (Exorcism of evil)

And to finally invoke Hume (through Sagan) is to call into question the existence of miracles.

The tearing down of SOLO might seem more like the actions of a spurned lover. Didau threw his all into SOLO in 2011 but SOLO failed to reciprocate. So, what better than ridding himself of all evidence that he had once loved.

In Didau’s blog we have not a refutation of the potential impact of the SOLO Taxonomy but a denial. He has attacked a strawman. In time, Didau ascribed certain claims to SOLO based on the needs of the inspectors of the profession at the time. And, in time, Didau found the needs of those inspecting the profession to be at fault, not SOLO. The deep implementation of SOLO has been shown to improve the Metacognitive (Flavell’s definition) prowess of pupils. And with greater Metacognition comes greater motivation to learn. We know from the work of Dweck and Hattie that improving these attributes is commensurate with increased student outcomes.

If teachers apply the SOLO Taxonomy to their teaching when, like Didau, they only possess surface knowledge of it, we see nothing more than a superficial change. The challenge and opportunity for teachers is to have a deep understanding of the SOLO Taxonomy, so that their impact on students’ learning will greatly increase.