Headings How
Science Works Search Questions 
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.
Headings How
Science Works Search Questions
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