TEACHING BY MODEL
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Using models in science teaching and learning

“…the fundamental fact about learning: anything is easy if you can assimilate it into your collection of models…what an individual can learn, and how he learns it, depends on what models he has available. (Papert)

Introduction

Within the scientific community models are an important mechanism for advancing scientific understanding. This involves the construction, validation and application of scientific models. Science instruction should be designed to engage students in making and using models where possible If scientists use models as ‘thinking tools’, shouldn’t students also use them? Teachers can use models to help students make sense of their observations, and understand abstract ideas through the visualisation of

• objects that are too big, too small or positioned so it is difficult for them to be seen easily e.g. an ecosystem, cell, heart
• processes that cannot easily be seen directly e.g. digestion
• abstract ideas e.g. particulate nature of matter, energy transfer.

When using a model of any type with groups of students it should be made clear to them that it is a model they are using. A teacher cannot guarantee that the way he sees a model, or wants the students to see it, is actually the same way that the students do. It is important to introduce the idea that models can change over time and that models need only be ‘good enough’ to explain a particular concept or idea to meet the needs at that time.Science students who become actively involved in using models in their learning have been shown to gain a deeper understanding of the concepts and processes about which they are learning

Types of scientific models

Type	Description and example
Scale models	Version of the original that is easy to see e.g. anatomical models
Analogue models	Simplification of the original used to explain certain phenomena e.g. different types of atomic and molecular models
Mathematical models	Express a situation in terms of formulae e.g. gas laws
Theoretical models	Put forward an explanation of a situation based on previous scientific knowledge, experiences and observations e.g. the ‘big bang’ theory

 
Models in science teachingThese can mainly be classified into two groups – scientific models and teaching models:1.     Scientific models (or consensus models) represent the widely accepted scientific view of a concept or idea. It provides a representation or an explanation for a complex process.2.     Teaching models are used to help a learner understand or visualise an idea, process or system; they are visual or physical representations which helps explain the abstract idea or invisible structure to the learner. Analogies as teaching models, usually illustrative rather than explanatory, are explanations or stories based on an object very familiar to students.It is very important that students know when a model being used, and what type of model is being used e.g. in one lesson a scale model of the ear may be used, in another a ‘slinky’ is used as an analogical model to represent the movement of sound. The teacher needs to point out to the students the differences betweens these two uses of models. Effective use of modelling

• makes explicit the purpose and use of the model as a process of thinking
• takes into account pupils’ prior knowledge and experiences – creates links between an idea they have seen before and the one they are about to see
•  is matched to pupils’ ability and maturity
• maintains the pace of the lesson by using modelling for short periods only
• repeats the modelling of a process whenever necessary - some skills are best acquired through repeated practice.

If used inappropriately models can lead to development of misconception that can be hard to replace - learners should be taught the scope and limitation of the models.

Science thinking skills associated with making and using models

• recognising the similarity between models and the things they represent, e.g. recognising what is and isn’t a model of the heart
• assessing the strengths and limitations of models in explaining and predicting the behaviour of the objects or phenomena they represent
• creating models to explain things that cannot be observed directly e.g. acquiring images and understandings that come from drawing, painting, sculpting, music, role play
• using models to raise questions, communicate ideas, and test hypotheses in many different contexts e.g. carrying out an experiment with a model that is not possible or practical to do with the real thing

Examples of teaching models used in school science

• Electricity: teacher and students all become part of the ‘Big Circuit’.
• Conduction, convection and radiation: Students model the processes of heat energy transfer by passing a ‘parcel of energy’ along a line of linked pupils for conduction, by circulating to pick up a ‘parcel of energy’ and delivering it elsewhere before circulating to pick up some more, etc. The teacher models radiation by throwing ‘parcels of energy’ across the space.
• Reactivity series: Cards with the names of the metals are handed out to the students and they have to arrange themselves in a line in the correct order of reactivity.
• Resistance in an electrical circuit: the ‘rope through the hands’ used in a circle of students.
• Charged particles moving in an electrical circuit: golf balls in clear tube.
• Feeding relationships in a food web: students acting as producers/consumers arrange themselves to represent the food web.
• Human lungs: balloons in ball jar / bottle.
• Absorption through small intestine: Visking tubing.
• Transfer of sound energy: ‘slinky’.
• Atoms, molecules and bonding: various commercial or self-made model systems.
• Joints/muscles, heart, eye, etc: anatomical or self-made models.

Examples of analogies used in school science

·       Money as an analogy for energy.·       Camera as an analogy for the eye.·       Squeezing toothpaste as an analogy for peristalsis.·       Scissors as an analogy for digestive enzymes.