This Instructional Activity is a part of the Lesson 3, Unit 4, Grade 8. We want to define "linear equation in x." Here are some examples of linear equations. Using what you know about the words linear (from Lesson 2) and equation (from Lesson 1), develop a mathematical definition of "linear equation in x." Consider developing a word bank or word wall to be used throughout the module. Show students the examples below, and provide them time to work individually or in small groups to develop an appropriate definition.