In order to properly interpret redox equations, it is necessary to know what has been oxidized, and what has been reduced. This PowerPoint presentation builds on other lessons to determine the oxidation states of every element involved on the reactant and product side of a redox equation. The equation is analyzed to see how the oxidation states have changed. The species with an increased oxidation state is identified as the substance oxidized, while the species with a decreased oxidation state is identified as the substance reduced. Worksheets on this topic are available free of charge on my website at www.evanschemistrycorner.com.