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.
Speciation—what will happen?
Below is the drawing I produced during the lesson with my students (aged 16-17). It began with Scenario 1. The students had learnt about natural selection, genetic drift, and allele frequencies previously, but they hadn't learnt about speciation. This was something new for them to discern.
There is a population on the left, and a sample of the population manages to disperse around a geographical barrier. They survive and establish a new population on the other side. In this scenario there are different selective pressures on either side of the geographical barrier. What happens next, in terms of evolution?
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, this part of the lesson is discussion and dialogue based, as students draw on their knowledge of mutation, natural selection, and genetic drift. I'm not simply explaining the it to them, I'm giving them time and space to mentally tinker with the concept to get a feel for its structure. To get a feel for what is relevant, and what is not.
Next we do the same with the scenario below with the only difference being that there is now the same selective pressures on both sides of the barrier. What happens?
As the discussion develops—with my guidance—the students discern for themselves the core idea of the separation of gene pools, and how this sends each down a path to speciation (contingent on gene flow between them).
Instruction next
Only now do I include a concrete example, looking at birds of paradise on the Indonesian islands, and this fantastic video showing how speciation occurs through reproductive isolation.
The video is a concrete example because it uses concrete elements, birds and their traits, real geographical barriers, a sense of time, rather than the abstraction I presented in my diagram. And I teach any specific details about the concept that students would never have discerned for themselves.
At the end of the lesson, I asked the students if they thought they would have learnt more if they'd seen the video first before discussing my diagrams and discerning the patterns. Unanimously, and confidently, they all suggested that the problem solving first approach allowed them to interpret and understand the video at a deep level. If you've liked this then check out my book. Download chapter 1 here—English edition—edición española—or check out my other posts. Another post on problem-solving-first can be found here.
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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.