In this lesson, students reinforce the circle connecting three fundamental ideas: a solution to an equation is a number that makes the equation true, performing the same operation on each side of an equation maintains the equality in the equation, and therefore two equations related by such a move have the same solutions. Students compare two correct solution paths for an equation, and then two incorrect solution paths, identifying the mistakes made. They solve equations mentally as they move towards a general method for solving linear equations. Finally, students apply their growing fluency in solving equations to constructing numbers puzzles. As students explain their reasoning for choosing a particular move while solving equations, they engage in MP3.

Grade 8, Episode 2: Unit 4, Lessons 4 & 5 | Illustrative Math