* No new substances are formed: The sugar and tea remain chemically the same. The sugar molecules simply disperse throughout the tea, but they don't change their chemical composition.

* The change is reversible: You can easily separate the sugar from the tea by evaporating the water.

* The change is primarily about appearance and distribution: Stirring changes how the sugar and tea look and are arranged, but not what they are at a molecular level.

Examples of chemical changes:

* Burning wood (changes wood into ash and gases)

* Rusting iron (iron reacts with oxygen to form iron oxide)

* Baking a cake (ingredients combine to form a new substance)