Learning goals: Teacher Facing Determine whether a triangle with given side lengths is a right triangle using the converse of the Pythagorean Theorem. Generalize (orally) that if the side lengths of a triangle satisfy the equation $a^2+b^2=c^2$ then the triangle must be a right triangle. Justify (orally) that a triangle with side lengths 3, 4, and 5 must be a right triangle. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from 8.8 Pythagorean Theorem and Irrational Numbers, Grade 8.