What are models?
Models are representation of an idea, object, event, process or system. Model is a very important teaching aid for science and geography teaching. Model has a three-dimensional effect on the mind of the students. They are the replica of the real subject matter. Sometimes clay, paper, plaster of Paris and varieties colour can be added to make suitable models of different objects.
Models and modelling play a crucial role in science practice. One justification for their inclusion in science teaching is that they contribute to an ‘authentic’ science education, where teaching reflects the nature of science as much as possible. Models helps in simplification of complex ideas this is by clarifying the structure of a complex phenomenon by reducing it to simpler and more familiar terms. Models allow learning to ask questions and a help us interpret the representation observed through questions.
Types of models
- Mathematical models
Mathematical models are very popular type of models used as teaching aids. This is used when there is the need to work out an object behaviour using equations. For instance the speed, acceleration and flight path of a ball traveling through the air can be modelled using (relatively) simple equations. The model may allow learners to change the ball’s size, weight, starting speed and so on (formally called the models’ ‘initial conditions’). This is the true power of mathematical model is that it allows learners to predict the future.
2. Mental model
Mental models are used to describe and explain phenomena that cannot be experienced directly. Scientists use mental models to think through abstract ideas and theories. For example in the representation of the molecular structure of benzene, there are many stories of the famous dream August Kekule where he saw dancing snakes biting their own tails, and realized the benzene molecule could be seen as a ring structure rather than a straight chain. This was his mental model. The expressed model he made as a result of his ‘dream’ helped others understand how the atoms could fit together.
Another example is the composition of atoms, when John Dalton started thinking about atoms he thought of them as if they were bowls or balls – this was his mental model. His experiments in 1802 supported the theory that matter was made of particles and he pictured them as small billiard balls. Using this model he was able to show how each element could be represented as being made up of the same kinds of atoms, and that compounds could be explained as being made up of atoms in specific ratios – this was his expressed model.
3. Expressed models
Expressed models used in science communication and teaching include: two-dimensional models, such as those found in textbook diagrams; three-dimensional models such as scaled miniatures (a smaller version of large structures); scaled enlargements (an enlarged view of something too small to be seen); and working models. For example, the structure of a cell can be represented as a scaled enlargement.
4. Digital models
Digital models include animated models and simulations. Simulations allow students to simulate a situation, such as making choices about land use. Animated models may also allow students to control variables to see what impact each variable has. These include animated models of science concepts such as cell division and tectonic plate movement, through to simulations of decisions about land use, etc.
Advantages of models
- Expensive prototypes do not need to be built
- No equipment is damaged
- People are not put in any danger
- Modifications can be made easily and re-tested quickly
- Time can be sped up/slowed down
- makes it clearer easier to understand
Disadvantages of models
- learners are at risk of learning the model rather than the concept it is meant to illustrate
- there might be cause where the learner may fail to distinguish between a mental image and a ‘concrete’ model
- there may be lack the necessary visual imagery to understand the model
- lack awareness of the boundary between the model and the reality the model is representing
- mix up aspects of two or more different model
- miss some key attributes and so misunderstand the purpose of the model
- learners may continue to use the least sophisticated of a range of models, even when they have been introduced to more advanced models
- A model may lead to oversimplification of a particular concept.
How to overcome learning challenges
Overcoming challenges associated with models requires careful teaching that focuses quite consciously on the model as an idea, object, event, process or system. A new model could be introduced in a sequence such as this:
- Introduce the idea that the model is intended to show and find out what ideas students already have about that event or pattern.
- Students should carry out the modelling activity themselves.
- During the activity or at the end if more appropriate, the teacher talk about how the model activity is ‘like’ what would really be happening and how it is different from real life situation.
- There should be clear identification of the positive features of the model (what is deliberately chosen to represent ‘reality’)
- The trainers/ teacher should show identification of the negative features of the model (what is deliberately excluded).
- The natural features should be adequately identified (what is ignored or not commented on).