Learn how to calculate sale price when combining two "percent-off" discounts in this video from KQED. In the accompanying classroom activity, students develop and share a variety of strategies, including modeling with a 10 x 10 grid to determine a total discount and sale price when two percent-off discounts are combined. They compare their strategies with the approach demonstrated in a video. To get the most out of the activity, students should be comfortable calculating discount as a percent off a dollar amount (e.g., 20% off an item priced at $50) and familiar with the concept of a ratio.