Scientific Measurement

Measurement is a key part of science. Scientists measure length, weight, volume, temperature, and time using precise tools. Measurements let scientists describe the world with exact numbers instead of guesses. Using standard units means scientists everywhere can understand each other's results.

Tools for Measuring

Different tools measure different things. Rulers and meter sticks measure length. Scales and balances measure mass. Graduated cylinders measure the volume of liquids. Thermometers measure temperature. Stopwatches measure time. Each tool gives a precise number with a unit attached.

The Metric System

Most scientists around the world use the metric system. Length is measured in meters. Mass is measured in grams. Volume is measured in liters. Temperature is measured in degrees Celsius. The metric system is based on tens, which makes it easy to convert between units.

Fun Facts

• The meter was originally defined as one ten-millionth of the distance from the North Pole to the equator.
• Scientists can now measure time so precisely that the best atomic clocks would not lose a second in 300 million years.
• The metric system was created in France during the French Revolution in the 1790s.

Did You Know?

In 1999, NASA lost a Mars spacecraft because one team used metric units and another used English units. The different measurements caused the spacecraft to fly too close to Mars and burn up. It was a costly lesson about the importance of standard measurements!