Thanks to the National STEM centre for the below blog post on 'Teaching Evolution at Key Stage 2'. The STEM centre is based in York and houses the UK's largest collection of STEM resources. Their eLibrary also offers a bank of fantastic free resources for the classroom. Find out more and visit their website.
The teaching of evolution at Key Stage 2 is a much talked about topic amongst the teaching profession. Apart from the cultural and religious perspective of many families, it is a topic that is also appears at first simple but is actually quite complex and open to misinterpretation.
So teaching it at primary level raises many questions…
There are those who believe that teaching the topic early will provide children with a greater awareness of evolution of life on earth. Children will have encountered it in nature programmes and will most likely have some awareness or questions about the diversity of life on Earth. Others believe that children in Key Stage 2 will misunderstand the theory and develop misconceptions which could make learning about evolution in secondary school more difficult.
This will always be a contentious issue. However, whatever your viewpoint, it now resides in the curriculum at Upper Key Stage 2. So let’s explore some of the challenges of teaching evolution and the resources available to help with this tricky topic. A good starting point would be to define the terms highlighted in the topic as they include two terms which, though linked, may best be looked at separately at first to avoid developing misconceptions.
Evolution consists of changes in the heritable traits of a population of organisms as successive generations replace one another.
Inheritance is those traits that an organism inherits from its own parents.
Children may believe that an animal can evolve in its own lifetime or in a one generation process. Evolution describes changes in inherited traits of a population of organisms through successive generations. It is populations of organisms that evolve not individual organisms and evolution takes place over a long time period. This is also a good time to point out that evolution happens in plants as well as animals and also in microorganisms!
These new resources from the STEM centre aim to help children at primary level understand the gradual process of evolution by showing it happen. They consist of two animations in which two children go back in time to watch the evolution of the whale and the horse. The children discuss the evolutionary changes that have happened, which lead eventually to the present day whale and horse. They also include colourful comics which highlight the evolution of several features of these animals and lead into various discussion points. The children compare the fossils of ancestors to the modern day skeletons of these two animals. In discussion it may be a good idea to remind children that the ancestor did not change within its lifetime.
The evolution of the whale is a nice example to use as it shows the evolution of a marine mammal from a land mammal. Over the course of many millions of years many species evolved from this ancestor and whales happened to be one of them. Another point to highlight this is that sometimes evolution may lead to the loss of a feature rather than adding a modification. In this example the animals limbs became modified into and fins and a tail, which were much more useful for life in the water.
The curriculum also asks us to identify how animals and plants are adapted to suit their environment in different ways. This area is open to misconception as adaptation arises via natural selection, which is not taught until Key Stage 3. Natural selection works because the variation between individuals in a population means that some are more likely to survive and reproduce than others.
A common misconception is that organisms can adapt in response to their environments. Examples include a polar bear having thick fur in the arctic or a giraffe having a tall neck to reach the soft leaves at the tops of trees. These adaptations have arisen as there was once a variation within the population of ancestor animals. The animals with the adaptation had an advantage over those that didn’t so were more likely to live longer and to reproduce. Some of the offspring will have the same adaptation and will then have a better chance of survival than an animal which does not have the adaptation.
A good way of showing this in class could be to carry out a simulation with have children playing the roles of two families of giraffes within a herd, those with long necks or with short necks. The giraffes with long necks will be able to reach the top leaves of the tree, the short necked family will not. Seeing that the short necked giraffe can’t grow its neck longer to reach the leaves will help them see that an animal cannot adapt to its environment in its lifetime. As it can’t feed on the leaves it will most likely die out before it reproduces. The long necked family of giraffes will eat the leaves and are therefore most likely to be well fed, healthy and live long enough to reproduce. When it does some of its offspring will most likely have long necks and will live long lives too. As time goes on more of the long necked family survive and the short necks die so many generations on the herd will be composed of mainly long necked giraffes. They could even model the ‘giraffe babies’ growing up and then eating the leaves of the trees, if their necks are long enough. This will help them see that this process takes generations and is happening to the population of giraffes rather than the individual animals.
The main point here is that an animal cannot acquire characteristics during its lifetime then pass these on to its offspring. It could be a good idea to not use the word ‘adapt’ when talking about an individual organism’s ability to survive in its environment. The word adaptation applies only to inherited characteristics that are useful for survival in the current environment.
Evolution is a difficult topic at primary level, in term of teacher knowledge and a child’s conceptual understanding. Further resources and support for teachers teaching this tricky topic at primary level may be found here.
If you have any ideas or resources to help teach this tricky topic why not add them to the STEM community resource area.
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