Three - Dimensional Aids : Specimens

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.

SPECIMENS

According to Schuller, Charles and Walter, (1957) 'a specimen is an object which is incomplete, or which is representative of a group or class of similar objects', examples -

1.     incomplete object-piece of a silk sari

2.     representative of a group - a leaf, a cow or a folder.

They can be perishable like a butterfly, flowers etc. or non-perishable like tiles, fabrics, stones, grains etc.

Specimens are inexpensive and can be easily collected from the same sources as objects. In some cases where original objects are not usable specimens can serve the purpose. Presentation of specimens in a class depends upon their size and the size of the group of students.

1.     if they are large, keep on a table and students can view them while remaining seated; example - large decorative earthen articles from Kutch or Rajasthan.

2.     if they are small, convenient and safe to carry, pass them around among the students during class time; examples - cloth pieces, paper designs, colour specimens. Label them before circulating

3.     if they are small, inconvenient and unsafe to pass around, call students individually or in small groups to the front, to study them during or after the class; examples - diamonds, butterflies wings, fine silver jewellery etc.

Always store specimens carefully for ready future use. Perishable items require special care. Any biological specimen can be preserved in a glass jar or vial with the help of chemicals like formalin, glycerine etc. Non-perishable or dry specimens can be stored in clearly marked wooden or steel cupboards or in shallow cardboard boxes. You may mount a dry specimen with glue, pin, tape or thread on a piece of stiff cardboard that fits well at the bottom of a shallow box. Label each specimen.