The targeting of misconceptions is seen as a critical skill in the teaching of science, but how can these pupil misconceptions be effectively targeted? Hazel Bennett offers some essential advice to teachers of science
|Science is an important part of the core curriculum. It is a fascinating, but difficult, subject and requires a depth of knowledge and understanding in order to be taught well. Primary school teachers, who do not possess a science degree, often find themselves teaching science topics which they have not been taught themselves. I have been in this situation and am acutely aware that it is extremely difficult to teach on the limit of my own knowledge. When we find ourselves faced with an unfamiliar topic, it is important to study it well in advance and read more than we need to know, because, if we are developing inquiring minds, there will pupils asking questions beyond the scope of the lesson.|
Unfortunately, science in the hands of a non-specialist, can lead to errors in teaching. The situation is made worse by the fact that some primary science books textbooks are not wholly accurate and pass on misinformation which is difficult for both teacher and pupil to unlearn later. So what are
1. Fair testing
In order to carry out an investigation, a child first needs to understand the concept of fair testing. At the beginning of Key Stage 2, children are just beginning to understand that, in investigations, you must change one condition only for your findings to be valid. I have never taught an infant who understood it. For example, when investigating what conditions plants need to grow, if they want to find out if plants need light, they must make sure that the plants grown in the dark have exactly the same amount of soil, water and warmth as the plants grown in the light. To children, it has to be emphasised that this makes the test fair, so that any difference in the plants grown in the dark can be attributed to the lack of daylight.
Secondly there are many words, which are in use on everyday life, which may have a certain meaning in science. The word ‘fair’ is one of them. Once, after an investigation, when the children had drawn a conclusion and I thought they had understood the activity, I asked, ‘How do you know that the test was fair?’ They all agreed that the test was fair because I had passed the apparatus round the table and let them all have turn. I learnt the lessons that any word with more than one meaning must be explained clearly, and careful questioning is needed to assess whether all pupils have grasped the concept. Also, sound understanding or the principle of fair testing only comes after a few practices and repeated explanation.
Many words used in science have very precise meanings, but in popular usage have different meanings – force, energy, power, pressure. Teachers need to be careful when reading any source material to check if the terms are being used scientifically.
Friction can occur in different ways. I have seen a suggestion in a school science book, where pupils were asked to time how long it took for various items to slide down a slope. The items included a matchbox, ruler, toy car and a marble. There was no mention that the marble and the toy car would roll, not slide. Objects which slide have much more friction than those which roll, and so they should not be compared, except to demonstrate the difference in sliding and rolling. The distinction between sliding and rolling is rarely made, but it is essential that it is explained carefully. The textbook even said that smooth, shiny surfaces caused less friction. Smooth surfaces cause less friction. Shiny surfaces have no effect on friction.
3. Cause and effect
Children in Key Stage 2, who are still at Piaget’s concrete level of thinking, often jump to conclusions and confuse cause and effect. Only after careful questioning can a teacher assess whether the concept has been understood. For example, they sometimes think that wind is caused by clouds moving along in the sky, or branches of trees shaking causes a breeze.
4. Temperature and pressure
Even some teachers believe that air cools as it rises because the upper atmosphere is cold. This is not true. As the air rises from the ground, the air pressure gets less and so the air expands and cools. Air which descends towards the ground becomes warmer because the air contracts as the pressure increases. This is demonstrated by pumping up a bicycle tyre. Feel the warmth of the entry nozzle. Release the air and feel how cold it is.
It is difficult for children to understand the concept of air having high and low pressure. In the mid-seventh century, Pascal suggested that we imagine lots of bags of wool, stacked on top of each other. The wool on the bottom bag would be thinner than the one on the top because of the pressure on it is greater. It is the same with air. The air on the ground is pressed down by the air above it, so the air pressure is higher at ground level than higher up.
5. Floating and sinking
Some people believe that light objects float because they are made of materials which are less dense than water, and some sink because they are made of materials which are more dense than water. This is not so. A ship made of steel floats because the density of the whole ship is less than the density of the water. A plastic duck, if compressed into a small enough ball would sink when its density became greater than that of the water. Remember, an iceberg floats because its density is less than that of water.
6. Damp air – heavier or lighter?
Damp air is often believed to be heavier than dry air. On showery or humid days, people say, ‘Isn’t the air heavy?’ In fact, damp air is lighter than dry air. A barometer will show higher air pressure in dry, sunny weather, than in thunderstorms. Damp air feels heavier because of its physiological effect on us. This is a case of believing that things are how they feel rather than how they are measured.
Sometimes textbooks are not accurate in details. Authors can use unsuitable analogies. I have seen a textbook which says that the moon reflects light like a mirror. The moon does reflect light but not as a mirror does, creating an image. It would have been better to say that the moon and planets reflect light like a gigantic mass of rock such as chalk. Analogies have to be accurate in detail as well as being within the understanding of the pupil.
8. Light reflection
Some text books say that light is reflected off surfaces. This is not wholly true. Most objects absorb some light. If you hold a page up to the sun, you will see that some light passes through it. Most light is reflected from within the body as well as the surface. The colours of most objects are caused by reflection from the inside. Consider the change of appearance of porous materials like sand or paper, if you pour water on them.
9. Generalising from limited knowledge
It is tempting to draw sweeping generalisations without enough information. One example is that conifers or cone-bearing trees are always evergreens and hardwoods are deciduous. This is true in many cases but, typically in biology, there are many exceptions. Larch, which is a conifer, is nonetheless deciduous; while holly is a hardwood, which is evergreen.
10. Confusions with material and structure
Certain materials remain unchanged but held in a different position, they become more resistant to being bent or broken. A ruler held horizontally can easily be bent or broken: the top side can be stretched and the under side can be compressed easily. If you rotate the ruler by 90°, so that the narrow edge is uppermost, it becomes very difficult to bend it because the upper edge needs more stretching and the lower edge needs more compression. The material appears to have become stronger although it remains unchanged. The structure is now stronger because the load has been distributed differently. This is the principle on which steel girders work. The ruler bends easily. The same ruler is very difficult to bend after being rotated by 90°.
So how can we avoid misconceptions?
The golden rule is never be afraid to ask for help. Primary school teachers are good at sharing skills. Teachers who trained in recent years have often had a more detailed science training than more mature teachers. Sometimes teachers are shy of asking because they dislike showing their lack of knowledge. This is unwise. It is part of a science coordinator’s job to help anyone who needs it and nobody is expected to know every detail of all subjects.
We also need to use the technology at our disposal. These websites and others contain displays to make the task enjoyable for both pupils and teachers.
BBC Bitesize, KS2 Science