Learning goals: Teacher Facing Calculate values that are a solution for a system of equations, and explain (orally) the solution method. Generalize (orally) a process for solving systems of equations using substitution. Justify (orally and in writing) that a particular system of equations has no solutions using the structure of the equations. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from 8.4 Linear Equations and Linear Systems, Grade 8.