Notes: Measurement

The process of using numbers to describe a quantity or process. What is measurement? The process of using numbers to describe a quantity or process. All numbers must have a unit of measure.

Why is measurement important? They allow us to describe processes and events.

Length- The distance between two points. Measured with a ruler, meter stick or tape measure. Units: meters (m), centimeters (cm), millimeters (mm), or kilometers (km).

Time- The interval between two events. Measured with a stopwatch or timer. Units: hours (h), minutes (min.), or seconds (sec).

Mass- The amount of matter in an object. Measured with a triple beam balance. Units: grams (g), milligrams (mg), or kilograms (kg).

Temperature- The amount of energy within a sample of matter. Measured with a thermometer. Units: Celsius (ºC), Fahrenheit (ºF), or Kelvin (ºK)

Volume- The amount of space an object takes up. Measured with: A ruler for regular objects (length x width x height) A graduated cylinder for irregular objects (water displacement method) A graduated cylinder for liquids (read the meniscus) Units: centimeters cubed (cm3), liters (L), or milliliters (mL).

Estimate- An approximate measurement of an object or event.

Metric System- A base-ten system. In this type of system, as the decimal point moves right or left, numbers are multiples or divided by ten. Sometimes called the International System of Units or abbreviated as SI.

US Customary Units- Standard units of measurement commonly used in the United States. Examples: gallons, ounces, pound, inches, feet, yard.

Accuracy- How close you measurement is to the actual value.

Precision- How close a group of measurements are to each other.

Errors in Measurement- Random errors- are not always predictable and can come from instruments or environmental issues. Systematic errors- are predictable, but always preventable, like uncalibrated tools.