Max had two pictures of triangles with exterior angle measurements given. Two sides of the triangles were congruent. I taught Max that if 2 sides of a triangle are congruent, then the angles opposite those sides are also congruent. We used the rule of supplementary angles to find one of the interior angles of the triangle. Supplementary angles add to 180 degrees. We then set up equations to find the missing interior angle, given that the 3 angles of a triangle add to 180 degrees. Max did well with this!