This Instructional Activity is a part of the Lesson 2, Unit 3, Grade 7. Students complete the table in the Opening Exercise that scaffolds the concept of opposite expressions from the known concept of opposite numbers to find the opposite of the given expression. Additive inverses have a sum of zero. Fill in the center column of the table with the opposite of the given number or expression, then show the proof that they are opposites. Encourage students to provide their answers aloud.