In previous lessons, students used diagrams and drawings to make sense of and solve two-step story problems that involved money. In this lesson, students continue to work with two-step story problems and decide if a given answer for a two-step story problem is reasonable. As in previous lessons, students may use any strategy that makes sense to them when estimating or explaining why an answer is or is not reasonable. The number choices encourage students to use front-end estimation and to consider friendly numbers (including those that would make 100), but students’ use of these strategies may vary.

Throughout the lesson, it is important to emphasize the ways that students evaluate the reasonableness of answers and not how close any estimates are to the actual answer. Emphasizing the latter can frustrate students and encourage them to perform the actual calculation first, before sharing their estimate. Also, keep in mind that student strategies may resemble rounding, but students will not formally round until grade 3.