This lesson focuses on mastering the calculation of total costs for multiple items and determining the correct change using addition and subtraction strategies. Students will learn the fundamental rule of aligning decimal points when adding prices, ensuring accuracy in their calculations. Through worked examples and practice scenarios, such as calculating the total for grocery items and understanding real-world payment situations, students will enhance their skills in both summing costs and figuring out change from transactions. The lesson includes hands-on exercises for students to practice calculating totals and change with a variety of examples, ensuring comprehensive understanding and application of shopping math.