LESSON: Measurement

Watch the following video on science measurement.

Observation is an integral part of the scientific method.  Hypotheses are accepted or rejected based on how well they explain observations.  Some observations have numbers associated with them and some do not.

An observation such as “the plant turned brown” is called a qualitative observation because it does not have any numbers associated with it.

An observation such as “the object moved 200 meters” is called a quantitative observation because it contains a number.  Quantitative observations are also called measurements.  The numerical component of the observation is obtained by measurement, i.e. comparing the observation to some standard even if the comparison is an estimate.  In terms of value to a scientist, all observations are useful but quantitative observations are much more useful.  Whenever possible, you should make quantitative rather than qualitative observations, even if the measurement is an estimate.

Consider the following pair of observations.

1. When the volume of a gas is decreased, its pressure is increased.
2. When the volume of a gas is reduced from 2.0 liters to 1.0 liter, the pressure increases from 3.0 atm to 6.0 atm.

It should be easy to see that a great deal more information is available in the second observation.

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