subject: Science For Kids (2 Of 3). The Challenge Of Teaching Young Children About Food Chains. [print this page] Over-simplification is a danger in science education. While over-simplification might get the point across, it can imprint on the young student a false knowledge that can remain for a long time. This impression in turn can cause resistance in later learning when future instruction may paint a different and more complex picture of the world. Food chains are a good case in point and I will try to explain the pit falls in simplified instruction.
Text books or the internet will often show a thrush feeding on an aphid, a snake on a rat, or a badger eating a snake. These are all unusual behaviours for these creatures, only possible in exceptional circumstances. The broader picture is that most animals are opportunists and will eat food that is easy to obtain and ideally needs the minimum of effort and danger. The limited amount of energy obtainable from very small prey, such as an aphid, means that only small birds such as blue tits will find it economic to forage for them. This fuller explanation is more satisfactory because it gives a sense of energy spent versus gained. In addition, the physical structures of an animal, in this case the bird's beak and weight, will also point to the general diet of the creature. And what is meant by a 'snake' which can be any of nearly 2,800 species, all with their own range of habitats and diets. 'Snake' is a meaningless designation. Only by explaining these finer points, does a food chain make sense.
The second fundamental error in dealing with food chains is that very few diets are so restricted as to make all levels of hunter and prey both linear and singular. It ignores the variety, thus creating a web rather than a chain. In addition there is the factor of the variability of this food web over geography and time, such as periods of drought. In such times of stress, carnivores often eat carrion, because it is plentiful; similarly, some creatures, such as crocodiles, will turn to cannibalism on the point of starvation.
The third misconception created by the concept of food chains is the suggestion that the creature eats the same food throughout its independent life. Juveniles of many creatures eat a different set of food to their adult counterparts, often determined by their size and, in the case of carnivores, their level of hunting ability. Showing food chains in diagrams can become problematic; the essence is providing notes to highlight these variables.
Food chain theory is a good introduction to other branches of biological sciences and can often be taught together to highlight these other factors that are part of ecosystems. Ecosystems are determined by physical as well as biological factors and each living creature in that environment has its own impact on the relationships. Ecosystems are not exact; they often blend gradually into other habitats, such as forest to savannah. Over time most ecosystems alter or 'mature', such as the succession of dominant tree species in an undisturbed forest, leading to a 'climax community'. All creatures need to be suited and adapted to thrive in that environment because each ecosystem has its own set of physical and biological factors. Ecosystems determine the creatures' position in the food chain within that environment. Some animals and plants can inhabit a range of ecosystems, and in the long term, this can lead to new species arising, providing populations that are isolated from each other. So, the bigger theories and ideas starting from food chains can lead to an understanding of ecology which in turn can lead to the introduction of adaptation and evolution.
The last in this series of three articles will focus on the challenge of teaching young learners in the digital age when, on average, student spends six hours per day in front of the screen. The impact of this will be explored including underestimating young learners' passively acquired knowledge.
