Knowledge would stand proud, square, and centre in any word cloud formed from the conversations I've held within earshot of my iPhone. 

I've used the word indiscriminately with little thought for the understanding of others; shooting quick from the hip. Since it's elevation as inspection focus, the return has been a carpet-bombing. Uncertainty and fear make a dangerous cocktail, and a Molotov by any other name still burns as bright. I confess I've played my part. I've been imprecise. This is my act of contrition. This is what I'm talking about when I talk about knowledge.

Declarative Knowledge

Declarative knowledge is knowing something that can be known. I've heard it called propositional knowledge, it's declared, it's proposed, it's spoken as fact.

• I know that the Earth is an elliptical geoid.

• I know that the Mediterranean separates Southern Europe and Northern Africa.

• I know that in 2014, Kenya was reclassified as a lower-middle-income country.

• I know the stages in which a waterfall is undercut, causing it to retreat upstream.

• I know that China’s Belt and Road Initiative will increase its soft power.

If you can picture a town cryer shouting it at the top of their lungs as they pace the high street we're talking about declarative knowledge. Can it be contested? Well, yes, sure, everything is contestable from a postmodernist point of view.

Procedural Knowledge

Procedural knowledge is knowing how to do something that can be done.

• I know how to draw a climate graph.

• I know how to classify a country based on its GDP per Capita.

• I know how to calculate the infiltration rate of different surfaces.

• I know how to determine the rate at which a waterfall retreats upstream.

• I know how to measure the increases in China's soft power resulting from the Belt and Road Initiative. 

Don't misconstrue know-how for ability; I know how to do a great many things that I can't actually do. An easy way to think about this is the three-point line; I've never successfully earned three points this way, but I know how to.

Where Declerative and Procedural Interact

As Geography features a great many processes, like the undercutting of a waterfall, it would easy to think that these would be examples of procedural knowledge. An earlier version of this blogpost made that error. Let’s look at an example.

Surface water evaporates. This is declarative knowledge. Knowing how the surface water evaporates is knowing a sequence of declarative knowledge. Let’s take a look at the steps.

It’s much clearer, when the steps are written out, that each step of the process is it’s own peice of declared knowledge. I know that molecules vibrate more as the energy level increases. I know that low density air rises in the atmosphere.

There is procedural knowledge tied to the process of surface water evaporating. The key aspect is that it’s knowing how to do something that can be done and I think the diagram below illustrates the difference clearly.

Substantive Knowledge

Substantive knowledge is the sum total of everything that geographers have worked out. It's the knowledge produced by the academic discipline of Geography. From abrasion and the antarctic circle to a yardang and a zeugen, this is the stuff of Geography.  

• The Earth is an elliptical geoid.

• The anthropogenic accumulation of greenhouse gases in the atmosphere drives climate change.

• A zeugen is a pedestal profile rock in an arid region. 

Understanding how waterfalls move upstream is substantive knowledge. Substantive knowledge is what we spend most of our time teaching. Explicitly. Clearly. If, as it was so eloquently phrased by the Geographical Association, Geography was a language, then the know-how and know-that of its substantive knowledge would be its vocabulary. I'd argue that a more beautiful vocabulary would be hard to find.

The substantive knowledge of Geography has taken a couple of thousand years to be accumulated. It's been passed down, from one generation to the next. Our academic discipline's substantive knowledge has been continually refined, improved, clarified, and critiqued. It is unsurprising then that there are tensions; disagreements among expert communities and multiple perspectives on the same issues. These are all part of Geography's substantive knowledge, and, if we are to consider them, then we must ask ourselves how we know what we know. This question takes us into the realm of disciplinary knowledge.

Disciplinary Knowledge

Disciplinary knowledge is, perhaps, best understood through fieldwork. Conversations over parent's evenings often sideline into recounts of fieldwork memories, falling in rivers, nipping down the pub instead of actually recording how the highstreet building was used, and the endless colouring in of land-use maps. Though episodic, these memories are of former students doing Geography and being Geographers. 

Disciplinary knowledge is how substantive knowledge is generated. Christine Counsell does a fantastic job when she describes disciplinary knowledge as "that part of the curriculum where pupils learn about the conditions under which valid claims can be made". How do we know what we know in Geography? That knowledge is disciplinary. 

• The shape and outline of plates can be shown by mapping tectonic events.

• The remote location of the Mauna Loa Observatory gives us confidence in the findings of the Keeling Curve.

• The structure of the Earth is revealed because the transverse S-waves can't travel through the liquid outer core.

• River gradients can be measured and graphed against flow rates.

Disciplinary knowledge tells us how we know what we know, and much of it is repeatable at a secondary level. Disciplinary knowledge is reproduced inside and outside of Geography classrooms every time we collect and analyse data, every time we interpret a graph or draw reasonable conclusions. Training Geographers is integral to the teaching of Geography, and if I'm talking about how we know something, I'm talking about disciplinary knowledge.

Powerful Knowledge

Michael Young (2010) defined his concept of powerful knowledge as 'knowledge that they (the students) would not have access to at home or at work and knowledge that takes them beyond their experience'. Young contrasted this powerful knowledge with everyday knowledge which he categorises as concepts that help students understand and make sense of their everyday environment and experiences. Everyday knowledge would be concepts which are constructed as students grow throughout their lives and are rarely taught explicitly.

I'm confident that every school in the country teaches some of Geography's powerful knowledge. We only need to consider volcanoes and earthquakes to move beyond the direct lived-experiences of most students.

Which means that when I'm talking about knowledge, we can be almost certain that I'm talking about powerful knowledge. I'll likely keep shooting from the hip, trying in vain to dodge bomber raids, but hopefully, just maybe, you'll also know what I’m talking about when I talk about knowledge.