Learning goals: Teacher Facing Calculate the area of a tilted square on a grid by using decomposition, and explain (orally) the solution method. Estimate the side length of a square by comparing it to squares with known areas, and explain (orally) the reasoning. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from 8.8 Pythagorean Theorem and Irrational Numbers, Grade 8.