This worksheet is intended to be used with the math lesson power point of the same title. It is intended to be used in conjunction with the power point as students follow along on the worksheet and work the problems before the answers are shown on the screen. This worksheet covers the same two mental math strategies as the power point and has the same exact problems. Following the lesson, students will have a quiz to see how much of the lesson they retained and to check how much they learned. It will be an Easel activity. There are two mental math strategies that this lesson covers. First, it covers the adding left to right mental math strategy using both two and three digit numbers with and without regrouping. The second mental math strategy is the break apart or decomposing strategy. Students use this strategy to add two and three digit numbers with and without regrouping. By the end of the lesson, students should be able to add larger numbers using one or both strategies.