Learning goals: Teacher Facing Recognize that multiplying an equation by a factor creates an equivalent equation whose graph is the same as that of the original equation. Solve systems of equations by multiplying one or both equations by a factor and then adding or subtracting the equations to eliminate a variable. Understand that solving a system by elimination or by substitution entails creating one or more equivalent systems that would enable us to solve the original one. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from Alg1.2 Linear Equations, Inequalities, and Systems, Algebra 1.