Video narration
How can a triangle, a trapezoid, and a parallelogram look so different but still use the same idea for area? Picture square floor tiles inside each shape. Area counts the square units inside. Different shapes, same rectangle idea: use a base and perpendicular height. For a parallelogram, multiply base six by height four: twenty-four square units. Use the perpendicular height, not the slanted side. A triangle is half of a rectangle: one-half times six times four equals twelve square units. For a trapezoid, average its two parallel sides before multiplying by height. With sides five and nine, and height four, one-half times fourteen times four equals twenty-eight square units. They share one area idea because you are counting the square tiles: multiply base by height for a parallelogram, take half for a triangle, and average the parallel sides for a trapezoid.