Testing a hypothesis

Yasmin Jayathirtha

fig-1 In the last few columns, we have looked at how to illustrate concepts studied in the classroom, essentially to demonstrate descriptive material from the text. However, in teaching school science, we must also consider other pedagogical uses of setting up and doing experiments.

The first is modelling, i.e., setting up experiments to prove or disprove a hypothesis. The hypothesis is usually arrived at by considering our observations and getting an idea that ‘it seems X occurs because of Y’. All of us do this almost instinctively, and experiments which model the situation allow us to determine whether the reasons we give for the observation we make are valid or not.

Modelling experiments also allow us to tease out the effects of various factors. This aspect is very important since the ‘real’ world is complicated and many factors act together. This can lead to results that are counter-intuitive and give a different picture than those drawn from our observations. Galileo’s inclined plane experiments led directly to Newton’s First Law of Motion. The first law is counter-intuitive when it states that ‘a body in motion continues in its path, unless compelled by an external force to change it’. But watch young children when they pretend to drive cars. They are constantly turning the ‘steering wheel’. All of us, from childhood, make models of the world we live in and build up pictures of natural phenomena and we know that we need constant force to keep things moving. This describes the world we live in very well, but does not give a general law for the whole universe.

The author works with Centre for Learning, Bangalore. She can be reached at yasmin.cfl@gmail.com

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