This week I had the honour of giving a keynote at the excellent #CogSciSci event hosted at Landau Forte Academy Sixth Form in Tamworth. In a rather over-full talk (sorry!) I set out to explore a range of ideas about mental models in science and how we need to be deliberate and thoughtful in how we support students to develop them.
You probably had to be there (!) but here’s a rough summary:
If we’re to support students to develop mental models that help them understand the world, we can’t just give them ours. They need to form their own – and those schema will take time to build and refine. Where students are not actively engaged in a deliberate model-forming process, we can end up with misconceptions and the all-too-common issue of task completion as a poor proxy for learning. It’s the capacity to explain that we’re after.
I set out six types of model-making, with various curriculum examples.
1. Scale, Context, Stories.
Here I argued that cells, for example, can seem weirdly abstract and disconnected from their context if introduced with the classic animal-plant comparison worksheet – rather than via some images of real cells in the context of tissues and organ systems. Then, with the respiratory system, there’s a story students should be able to tell – at a depth appropriate for their age/stage. The sheep’s lung demo (which I LOVE) has to support the form a model for the millions of alveoli acting as sites of gas exchange.. it’s not just showing some offal on a slab, then getting a labelled diagram stuck in your book. The explanatory story has to connect macro to micro and vice versa.
A second example was the story that lies like a brilliant easter egg in the National Curriculum for KS2, linking Rocks to Evolution via the concept of the age of the Earth, the scale of time, the fossil record, the dinosaur evolution and extinction story and the glorious tree of life with the embedded notion of common ancestry. We did not evolve from chimps; but we have common ancestors. And whales and hippos are more closely related to each other than to anything else. If you know the story, you can tell it. It links ideas up; it helps build a mental model for the scale of time that is needed for evolution to make sense.. through the slow change processes that are revealed through rocks. (This is why science is the best!)
2. Particles. Imagining
Here, I talked about the central idea of particles in explaining phenomena. For students to understand states of matter, diffusion and numerous other issues, they need to be able to imagine the particle behaviours. That can be done explicitly – as I explored via an account of a Y5 lesson I’ve seen where the teacher did this brilliantly; each child imagining water molecules in their beaker of water; in their ice cube; in their freshly made condensation. I also touched on the power of PHET animations and the issue of separating states of matter from inherent material properties ie water can be a liquid, solid or gas – but so can iron and oxygen, if the conditions are right.
3. Real and Abstract
The issue here is to make the study of science about explaining and exploring real things; our abstractions are tools; they are not the real thing. Real life complexity informs the simplified models we make. So, let’s have children pooting for ladybirds, looking at real flowers and growing a bean. Each!
Practicals have experiential value sometimes. We don’t burn food because we can meaningfully compare the energy released by a crisp or a peanut (too many variables) – but we can gain tacit knowledge about energy being stored and then released in foods. The fact that food burns brings the energy transfer conversation alive. And if you want an example of an experiment for being a terrible fair test, look no further!
With chemistry there important concepts to drill home – ie that elements are made of one type of atom; it’s our basis for organising basic building blocks of materials – you can’t create zinc or iron when you heat copper carbonate (as I’ve heard some y11s guess to their teacher’s dismay). That all needs to be explored explicitly when students do experiments or see demos; the periodic table and the ‘elemental-ness’ of elements needs continual reinforcement. When reacting Sodium in water… you only have three types of atoms there. etc etc
4. Spatial Models – and more scale.
Here I was looking at a range of space-related phenomena to illustrate how important it is to support students in forming sound spatial models for objects in order to understand the scale and orientation of cosmic objects. The diagrams and images we use play a vital role. There’s a fabulous story around the Earth as a supremely isolated planet in the vastness of space – bring on Carl Sagan and the Hubble Ultra Deep Field. Then, every-day phenomena like day/night and sunsets need students to have opportunities to create mental images of a rotating planet at a distance from the sun. (You can’t take them to see a sunset and demonstrate that it takes exactly two minutes to drop over the horizon – but you can create the impression with images and a story). Moon phases need a good 3-D orientation and sense of scale to properly understand and here, you can get the class to track the moon with their own eyes. For A level students looking at gravity, a good 3-D field model helps explain all kinds of phenomena such as satellite orbits.
5. Processes; Misconceptions.
Here I used the example of global warming and climate change via the function of wind turbines, inspired by a hilarious YouTube video where some young men discover that one of their friends had thought wind turbines were designed to cool down the Earth – like giant fans – rather than being a renewable means of generating electricity. If we want students to understand the concept ‘net zero’, a whole range of processes need to be explored and connected: greenhouse effect, temperature equilibrium in balance with the carbon cycle, now disrupted by fossil fuel combustion and so on…
Ideas about heat transfer need mental models too – trapped air as a good insulator is relatively easy, but shiny surfaces as poor emitters – as with a hypothermia blanket – is harder to explain, for anyone!
6. Electromagnetism, Relationships
This final section looked at the very tricky area of electricity. Again PHET simulations can help connect students to ideas about charge, explaining something they can see with their own eyes – a rubbed balloon sticking to a wall – with a model of repelling charges and induced polarity. I revealed the story behind my teaser… oranges, a net and the Starsky and Hutch car? Well, this was about Mr Taylor, my secondary science teacher who had his Ford Capri painted with a Starsky stripe! He had an analogy of throwing oranges through a net to explain electrical current. Energy of throw = Volts; size of net holes = resistance and then number of oranges passing through per unit time = current. It kind of works in its convoluted way!
The key point here is that observable phenomena in electricity – and science in general – need a conceptual home in a model that students can fall back on. It’s no good trying to remember formulae by heart with the triangle method; you need to have something more fundamental that makes intuitive sense: current = potential difference/resistance makes sense. It’s the foundation. These PHET simulations are great – especially where they have voltmeters as probes, not hard-wired, reinforcing that we are comparing the potential between two places in the circuit.
I didn’t quite get onto the F= BIL issue but I’m firmly of the belief that too many students have insufficient exposure to real world manifestations, making motors and getting a really good intuitive sense of the mutual perpendicularity of field, current and force.. such that the left-hand rule is largely guessing and confusing!
So… lots to think about! Every area of science has an underpinning mental model and it pays to explore these things explicitly, deliberately, repeatedly, involving all students and checking their understanding by hearing them explain things, not just testing for bits of facts and setting a few problems.