Temperature is how hot or cold something is.

Something that is very warm.  Fire is very hot.  A summer day can be hot.  

Something that is very cool.  Ice is cold.  A winter day can be cold.  A soda can be cold.

A temperature that is between cool and hot.  The weather on a sunny day might be warm.  A dinner might be warm.

Things can be a little bit cold.  This is called cool.  

A thermometer measures the temperature.  A thermometer shows how hot or cold something is.

A unit that is used to measure something.  Temperatures is measured in degrees.

The system used to measure temperature in some countries.  The United States of America measures temperature in Fahrenheit.

The system used to measure temperature in most countries.  Celsius is part of the Metric System of measurement. 

Something freezes when it is below 32 degrees fahrenheit, or below 0 degrees Celsius.  Frozen water becomes ice.