Evolution is one of the most powerful ideas we have to understand our place in the universe,” says Laurence Hurst, director of the Milner Centre for Evolution at the University of Bath.

Since the idea was proposed by Charles Darwin in On The Origin of Species in 1859, evolution has grown to become one of the central tenets of our understanding of life on Earth. It is now accepted as scientific fact (even if it is still often referred to as a theory) and it is a staple of the national curriculum, to be taught at secondary and, since 2014, in primary, too.

But teaching this topic can be challenging. The subject requires the comprehension of vast timelines and complex scientific concepts, from DNA and genes to natural selection and adaptation.

Even for young learners, studying evolution means getting to grips with some complex ideas, from recognising that “living things have changed over time” to identifying “how animals and plants are adapted to suit their environment” and how these adaptations represent evolution.

For Hurst, the inclusion of evolution on the primary curriculum was the catalyst for a multi-year project exploring how it could best be taught to primary learners, in a way that enabled their teachers to feel confident in the delivery.

“We talked to a number of primary school teachers concerned about [teaching evolution] because, unlike secondary school teachers, the last time many did science was years ago,” he explains.

So, beginning in 2014, he and his team set about conducting large-scale randomised controlled trials (RCTs) with more than 2,500 children, in 96 classes in 45 primary schools around England, with teachers using resources created by the researchers.

Each teacher taught four lessons to their pupils, with different groups tackling the topic in different ways.

Teaching about Charles Darwin and evolution

The first lesson was the same for all groups, looking at the idea of variation by considering handspan size and eye colour. The third lesson was also the same for all: it was called “The Great Toilet Roll of Time” and was designed to help children understand the huge timescale over which evolution has happened by plotting major evolutionary milestones along a roll of toilet paper.

But lessons two and four were changed depending on which control group teachers were in.

In lesson two, children learned about natural selection by looking at peppered moths and how well camouflaged they are against certain backdrops.

The lesson looked at the black moths that grew in abundance during the 1800s, when the soot from factories meant that they were well camouflaged. This was used to demonstrate how environments can favour one species over another, enabling certain traits to become dominant.

In one group, children learned about this through a student-centred, active task, where they pretended to be birds hunting these moths against different backdrops. In the other group, the teacher delivered this information through a story and then set a written task.

In lesson four, children learned about homology (the similarity of gene structures) either by looking at the human pentadactyl limb (a limb with five digits) or at the fossils of trilobites (a group of extinct marine arthropods).

The researchers had a clear expectation of which group would perform best when it came to measuring their understanding of evolution.

“Current educational discourse holds that effective pedagogy requires engagement through active student participation with subject matter relating to them,” they noted in their paper in the journal Science of Learning.

So, this would mean the passive, non-human-orientated lessons would lead to the least effective understanding of evolution.

In fact, the researchers observed a very different outcome.

“The prediction from prior literature was clear that the teacher-focused non-human [material] should be [understood] the worst - [but] it was the best,” says Hurst.

Specifically, the passive and non-human-related lessons showed a 50 per cent higher effect size than the least impactful in terms of the difference between pre- and post-levels of understanding of evolution.

This is not to say that the other teaching resources did not work at all - all students showed improvements and the control group that had been expected to be best was second - but for Hurst, the fact that the supposedly weakest style delivered the best outcomes is evidence that teacher-centred, passive learning can be an effective pedagogical method.

“This notion of active versus passive is really about engagement,” he says. “A storybook, if properly constructed, can be extraordinarily engaging.”

Another factor for pupils in the teacher-led group performing best was the removal of the potential for misunderstanding and misinterpretation.

“We were discovering students could make false inferences from the experimental approach,” Hurst continues.

“For example, if we asked, ‘black moths went up over time when trees got covered in soot - why do you think that happened?’ they could say that maybe the moths were getting covered in soot as well.

“That’s a reasonable explanation but the storybook provided would then suggest that wasn’t right whereas, if you were leaving it to the students’ imaginations, they could be coming up with the wrong inferences.”

Eureka moment

Of course, this requires a skilled teacher to spot and correct such issues should they come to light - and when evolution was first added to the curriculum, many were concerned that they lacked the knowledge to actively teach the topic.

As such, as well as offering teachers the resources from this project to download, Hurst and the team have created a free online course designed to help teachers reach a GCSE level of understanding of the topic, in order to give them “confidence and clarity over the basic ideas”, and it’s available to those in primary and secondary.

And for those secondary staff wondering how they should be approaching evolution: Hurst and his colleagues have been exploring this too, with another major project involving 80 schools and more than 2,000 pupils.

The researchers were surprised to discover that the curriculum requires both evolution and genetics to be taught but that the two are not linked together as a teaching unit, he says.

“As evolutionary geneticists, we found it hard to understand how you can understand evolution without understanding genetics [first],” he explains.

The team set out to explore this relationship, monitoring the learning outcomes of the two topics depending on which way around they were taught. The conclusion was simple but profound: if you teach genetics and then evolution - irrespective of the content or methods used to teach the topics - the understanding of evolution goes up by almost 10 per cent.

“That’s a GCSE grade boundary, just by changing the order of teaching,” Hurst says. “It’s probably the simplest win-win, no-cost intervention imaginable.”

But why does it work so well that way round? Hurst hypothesises that by helping students to understand the building blocks of genetics, we prime them to comprehend the concept of evolution.

“If you understand DNA, you understand what a mutation is, you understand how mutations are transmitted, and understand they must exist at some frequency in the population and that they can go up or down - and that going up or down is evolution,” he says.

Around 47 per cent of those teachers involved in the research were already teaching this way around. For many of the rest, though, the explanation that teaching genetics first yielded better outcomes in evolution came as a eureka moment.

“A lot of them said: ‘Oh, that’s so obvious! Why didn’t we do that?’” says Hurst, adding that the vast majority - more than 90 per cent - then switched to this way of teaching.

It just goes to show that once a good idea takes hold, it quickly becomes dominant - something Charles Darwin knew a thing or two about.

Dan Worth is senior editor at Tes

This article originally appeared in the 11 June 2021 issue