Let's face it, December is Exhausting for Teachers! Save yourself some time with this common core aligned, high-interest lesson that focuses on percent discounts and sales-tax calculations. Santa is having a bad day, in walk your students (elves) to help Santa on a last minute shopping trip. This activity will keep students interested with little or no prep time on your part. Students will use a coupon to calculate the discount price of interesting Christmas gifts and then calculate the final price by calculating the sales-tax. Bonus: Have students act as the "cashier" to check each others work and write explanations for what they did wrong.