Given the task definition and input, reply with output. You are given a background paragraph that describes one or more causal or physical relationships, such as a relationship in economics, scientific law, or nature. You need to come up with a fictional story that makes use of the concepts or the relationship described in the provided paragraph. Make sure that your story does not repeat the relation in the given paragraph (e.g., by avoiding verbatim copies of the given paragraph). Start by reading the background paragraph, and determine what relationship(s) are in the paragraph. Write a story that involves the relationship(s) that you determined are in the background paragraph. Try to use your own words as much as possible and not repeat the background paragraph. Feel free to make up places and events as long as they tie back to the background paragraph in a way that you can ask a question about.

Background Paragraph: A catalyst is a substance that increases the rate of a chemical reaction. A catalyst is a substance that increases the rate of a chemical reaction. The presence of a catalyst is one of several factors that influence the rate of chemical reactions. (Other factors include the temperature, concentration, and surface area of reactants.) A catalyst isn't a reactant in the chemical reaction it speeds up. As a result, it isn't changed or used up in the reaction, so it can go on to catalyze many more reactions.
Henry and Tiffany are performing chemical reactions in their high school chemistry class. Henry performs his reactions with the use of a catalyst. Tiffany performs the same reaction with no catalyst present.