Energy tends to dissipate through the universe. As a result the overall entropy of the universe is always increasing. For secondary students, entropy is best understood by its relationship to randomness or disorder. This PowerPoint presentation provides a basis for students to understand when the entropy increases or when it decreases during chemical or physical changes. It also explores the natural tendency for entropy to increase, and provides examples that illustrate why it takes work to decrease entropy. The relationship between enthalpy and entropy in natural systems is explored, particularly with regard to the spontaneity of chemical and physical changes. The Gibbs Free Energy equation is presented, explained, and applied.