expands or contracts
Many thermometers measure temperature with a liquid that expands when it gets warmer and contracts when it gets cooler. Look at the common household thermometer pictured in the Figure below . The red liquid rises or falls in the glass tube as the temperature changes. Temperature is read off the scale at the height of the liquid in the tube. To learn more about measuring temperature, watch the animation Measuring Temperature at this URL: http://www. sciencehelpdesk. com/unit/science2/3.