Unit 5, Lesson 7
Adding and Subtracting to Solve Problems
Grade 7
Preparation
Lesson Narrative
In this lesson, students apply what they have learned about adding and subtracting signed numbers to represent situations and solve problems. First, they examine a situation in which changes in inventory are represented with positive and negative numbers. They interpret what the numbers mean in the context and calculate the new inventory amount after the next change. Then, students write expressions to represent multiple, sequential changes in elevation. This builds on previous lessons where students worked with representing one change in elevation at a time. As students explain how the expressions represent the situations, they construct arguments and critique the reasoning of others (MP3).
The last activity is optional because it provides an opportunity for additional practice with finding distances and differences in a geometric context.
- Apply addition and subtraction of signed numbers to solve problems in an unfamiliar context, and explain (orally and in writing) the solution method.
- Interpret signed numbers used to represent gains or losses in an unfamiliar context.
Let’s apply what we know about signed numbers to different situations.
Required Preparation
For the digital version of the activity, acquire devices that can run the applet.