THREE - DIMENSIONAL AIDS
Direct, purposeful experiences are not always available and if available, are not always usable or applicable in making the teaching very effective. To teach a concept of wild life and its preservation, it may not be possible to visit all the wild life resorts and show all those animals to the students. Some experiences belong to remote past or future and so it is not possible to experience them in reality. A real human eye or any other human organ may be available but for a detailed study, they may prove to be useless as their handling may be awkward. Thus, sometimes, the real things are too large or too small for easy handling.
In these circumstances contrived experiences help to simplify
teaching by editing the realities. Some complicated or distracting details are omitted, and some new ones are added and the sizes are changed for the sole purpose of better understanding of the original things. Such contrived experiences are provided through objects, specimens, models, mock-ups, mobiles and puppets.
A model is a three-dimensional, recognisable imitation of an object. A model may be the same size as the object it represents or it can be smaller or larger. It can be handled and seen from a number of angles. Models can be of many types.
A scale model has the correct representation of the thing through the exactness of the scale. It can be either enlarged or reduced depending upon the need; examples - insects, buildings, etc.
A simplified model is roughly the external form of an object, used mostly for education of children and illiterate persons; examples- birds, fruits, pots, etc.
A relief model also known as a relief map is a realistic, recognisable, representation of a country or a part thereof; examples - India, Gujarat. This is mostly used for teaching elevation in geography; however, a relief map proves to be very useful in understanding the life of people living in a particular area; examples - Himalayas and plains of Rajasthan.
A working model shows how things function in a simple way. Process and mechanism can be understood better by the use of a working model; example - working of human heart, washing machine etc.,
Cross Section Model
This type of model shows the internal structure of an object as it is cut crosswise. It is useful in teaching physiology, nutrition and technical topics; example - models of brain, eye, compost pit, smokeless chulla, etc.
Models are used when real objects are not usable.
Besides these, they are also used
1. to express abstract ideas and processes; examples-digestive system of body.
2. when flexibility is needed to teach by moving the articles which originally are either too big or static;, examples - houses and their arrangements; layout of a garden, etc.
Remember that models:
1. require professional skill in preparation
2. can be expensive
3. are breakable.
They can be bought from the educational material stores, or can be borrowed from leading libraries, universities and museums, besides being prepared by professional artists, teachers and students. They can be made from a variety of materials such as cardboard, wood, metal, wax, clay, plastic, plaster of paris, plasticine or cotton.
Using Models in the Class
Before the class meets, check that the
1. scale of the model is correct - Colour of the model has not faded
2. model is not damaged.
During or after the class, models should be properly positioned where they can be seen by everybody and handled if necessary for personal study. If the models are not checked and used properly, misconceptions may arise. So precautions should be taken as follows:
1. for enlarged or reduced models, the scale should be clearly specified.
2. real weights of fruits and vegetables, if different from the models, must be clarified.
3. if possible, original objects or the colour samples may be brought to the class to show the real colours of the objects, if the colours of the models are different from that of the original.
Models must be stored properly to avoid damage through dust, strong light and pressure of other articles. If not, they will break and their colours may fade. They can be stored in conical cupboards with glass tops or cupboards with glass fronts, to serve the purpose of their permanent display.