In this Science Max Quiz, Phil explains how to differentiate chemical and physical changes. He mentions that chemical changes produce new molecules, while physical changes don't. He includes several examples of both physical and chemical changes.
Beakman challenge: drink punch out of a glass with two straws: one inside the glass and the other outside. The straw outside of the glass causes the air pressure inside the mouth to match the outside of the mouth. Now you don't have the ability to get the liquid to move into the mouth due to the air pressure change since it's the same.