This resource focuses on understanding the concepts of elastic and inelastic goods, emphasizing how the availability of substitutes and necessity influences consumer behavior regarding price changes. Students will learn to categorize various goods as elastic (luxuries that people buy less of when prices increase) or inelastic (necessities that people continue to buy regardless of price increases). The document includes activities such as The Great Categorization, where students sort items into elastic or inelastic categories, and Think-Pair-Share discussions that encourage reflection on why certain items are regarded as necessities or luxuries. Additionally, it explores the role of substitutes in consumer choice and provides a challenge task to illustrate how the introduction of a substitute can change an item from inelastic to elastic.