In one of the hands-on investigations, as part of Discovered program, we had a fun activity that models the circulatory system of the human body. This is a learning from teaching that particular investigation.
Models are an excellent tool to teach science. But not all models are exact replicas of the system that is being explained.
Even though every model requires a certain degree of abstract relation between the components of the model and the components of the system, each of them would have a slightly different level of abstraction.
- For example , a physical model of the eye would have convincing similarity to the way a real eye looks. If it is a scale model then there is similarity in proportions of the original system [eye] and the model itself.
- But when we use the model to talk about how the lens in the eye works, it requires a bit of imagination to see how the lens of the eye changes its shape using the lens in the physical model [That does not actually show the change in lens shape of eye].
- If we talk about how the lens helps in focusing the image on the retina, the physical model is not much help as the person has to imagine how the lens would work and how the image is focussed onto the retina.
The same model has increasingly higher levels of abstraction required by the learner in the 2 and 3rd example. This is because the comparison between the model and the original phenomena is not similar.
The working of lens in the eye could be better explained using a drop of water and how its focal point changes when it is stretched. The thicker the water drop, the more different the image. This changes much like the lens in the eye. This requires less effort by the learner to relate both phenomena.
Similarly, for explaining the way image is focussed on the retina, we could use a convex lens on an optical bench to focus a picture on a white screen. This is far easier for the learner to relate to than just explaining about focus using a clay physical model of the eye.
Thus, I believe when designing a model for use in a classroom, one must keep this abstraction minimal. But the discussion is open.