Glucose homeostasis—What will happen?
On the surface we have the learning of the component parts of the human body that function as a system to control the levels of blood glucose. Students must learn the structures and their functions in order to get marks on exams. But at a deeper level we find the concept of the flows of energy and matter, and how organisms self-regulate (using feedback) to maintain them.
With an instruction-first approach teachers would simply explain both the deeper concept and the surface features. But as with many things in biology, so much new vocabulary can focus students' attention on memorisation, leaving them cognitively overloaded to deal with seeing the deeper concept.
On the other hand, in this example, beginning with a conceptual problem to solve can help students find meaning first. They see the system before the parts. Let me show you.
I begin by encouraging students (in this example aged 14-16) to find meaning in how the blood glucose levels relate to the flow of energy to body tissues. To do so, I produce a simple stock and flow diagram:
There is a lot that can be got from this simple model, and at first I ask students to tell me what they can understand from the diagram I don't explain it, I begin by setting up dialogic feedback loops for me to adapt to the class.
The most important aspect I want my students to see is how this model could lead to variability in the rate of flow to body tissues—a problem for a living organism. Flow rates would be high during and post-meals, but very low between feeding. Getting students to see this often requires guiding questions. And so this is where I point their attention, by asking them to discern the difference in performance of this system in an organism that feeds often, and one that feeds intermittently.
Take note. This is a key to the pedagogy of problem solving before instruction. You should present two situations that differ in only one aspect (or as few as possible), and then ask questions along the lines of: What's happening here? What's the difference? What are the implications?
So, students are asked to mentally tinker with the model to see how variety in conditions causes a variety in performance. This kind of problem solving—before I teach them any answers—allows students to get a feel for the concept at hand and so better attend to the relevant aspects that I will teach them. They get to "see the system before the parts", they get to separate the relevant from the non-relevant.
Ference Marton (2014) would call this "building a relevance structure". In simple terms—getting a feel for—and recognising—what is relevant from all the other less relevant factors.
Through discussion & questioning students can realise—for themselves—that an additional store is required to buffer the variability, and stabilise blood glucose levels. Here they discern the problem and predict a solution before I teach them what has actually evolved in organisms.
From here then, we can add to our model. And discuss the mechanism for how the blood glucose variation can be buffered via feedback loops. Again, through discussion and questioning students can come to discern a feedback mechanism themselves. And from here I can add in some more details—the hormones insulin and glycogen—things they could never have learnt without being provided with the information.
A stock and flow diagram that models the blood glucose system. This is a type of diagram called 'stock and flow'. The little triangles represent 'taps' that can regulate the rate of flow through a tube. The insulin arrow points to the 'tap' that controls the flow rate to the liver. The more insulin, the higher that flow rate.
Once the the deeper concept of the system has been seen, it should be easier for students to add in the concrete parts, overall mechanism, and details we see in the human body.
My books: Difference Maker | Biology Made Real, or my other posts.
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Two recent meta-analyses have both found that for conceptual knowledge (not procedural knowledge) problem-solving before teaching is more beneficial than the reverse (Chen and Kalyuga 2019; Sinha and Kapur 2021). For procedural knowledge, it seems the best bet is to teach them first, but most of what we teach in biology is conceptual.
Ference Marton (2014) discusses the principle as giving students a chance to—mentally or physically—tinker with a problem to see what is relevant and what is just a surface feature. Then when the instruction begins they have a better grasp of what to focus on. In fact, Chen and Kalyuga in their meta-analysis mention the same idea, suggesting that cognitive load is reduced during the instruction phase by first having a chance to tinker with an idea.
This post shows an example from my classroom of how I've carried out problem-solving-first without it being an unguided mess. Another post on problem-solving-first can be found here. And more research & examples in my book.
References
Chen, O., and Kalyuga, S. 2019. “Exploring factors influencing the effectiveness of explicit instruction first and problem-solving first approaches.” European Journal of Psychology Education 35: 607–624.
Marton, F. 2014. Necessary Conditions of Learning. London: Routledge.
Sinha, T., and Kapur, M. 2021. “When Problem Solving Followed by Instruction Works: Evidence for Productive Failure.” Review of Educational Research 91 (5): 761–798.