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How Science Works

Making Measurements to get the Evidence.

To get evidence we need to make measurements.
But what kind of measurements?
What do we measure? How do we make the measurements?

It depends on what we are investigating.
We can make measurements
by direct observation or by using instruments.

Direct observation means that we are just looking at something.
For example we can count the number of bubbles of oxygen
being given off by an underwater plant during photosynthesis.

There are also a very large number of instruments which we can use.
Examples of instruments include simple things such as a ruler or
a thermometer or a stopwatch or a weighing machine or a voltmeter
or the instrument might be very complex and expensive
such as a spectrometer or a telescope or an electron microscope.

The actual things that we measure
(for example length,  temperature,  time,  weight,  voltage)
are called variables.
The measurements which we make provide us with the data
 which can be used as evidence.

How sensitive an instrument is
tells you how small a change it can detect.
A change in a variable might not be detected at all
if the instrument does not have enough sensitivity.

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