During this lesson, students will learn the difference between estimation and guessing. Knowing how to estimate is an essential skill that will help students determine approximate totals as well as check the reasonableness of their answer to a problem. After listening to the book Betcha by Stuart J. Murphy, the students will be given opportunities to practice the strategies that are presented, in addition to finding the mean, median, mode and range. This lesson plan was created as a result of the Girls Engaged in Math and Science, GEMS Project funded by the Malone Family Foundation.