Massachusetts Department of Elementary and Secondary Education 45 min(s)

In this lesson, students will construct arguments using objects, pictures, and equations to make sense of change unknown, addend unknown, and difference unknown story problems. One class period Sample Problems for Detective Journals (see end of lesson) Cubes/objects for students needing to act out problems. By the end of this lesson students will know and be able to explain how and why they used properties of operations/inverse operations to translate their situation equation into a solution equation.