Temperature
Elementary School
Definition
A measure of how hot or cold something is, related to the average energy of the particles in a substance. Temperature is measured with a thermometer in units such as degrees Celsius, and differences in temperature cause heat to flow.
Worked examples
Water freezes at \(0\,^\circ\)C\(\) and boils at \(100\,^\circ\)C\(\) at standard pressure.
Temperature tells us the thermal state of water at these key phase-change points.
A cup of hot tea at \(80\,^\circ\)C\(\) placed in a \(20\,^\circ\)C\(\) room cools as heat flows from tea to air.
The temperature difference drives heat transfer until both reach the same temperature.
Common mistakes
- Temperature and heat are the same thing. → Temperature measures average particle energy; heat is the energy transferred between objects. A large ice block can have more total heat energy than a cup of boiling water despite lower temperature.
- Adding the same heat to any substance raises its temperature by the same amount. → Different substances have different heat capacities, so temperature change varies. Water heats up more slowly than metal because it takes more energy per degree per gram.
- \(30\,^\circ\)C\(\) is twice as hot as \(15\,^\circ\)C\(\). → Celsius is not a ratio scale; use Kelvin for meaningful ratios of thermal energy. \(30\,^\circ\)C\( = 303\,\)K\(\) and \(15\,^\circ\)C\( = 288\,\)K\(\), not a 2:1 ratio.
Where you'll use it next
You'll use temperature when studying thermal expansion, gas laws, phase changes, calorimetry, and chemical reaction rates in chemistry and physics, plus climate and weather systems in Earth science.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026