Area and perimeter

Area and perimeter help us measure the size of 2D shapes. We’ll start with the area and perimeter of rectangles. From there, we’ll tackle trickier shapes, such as triangles and circles.

Transition from counting unit squares to multiplying side length to find area. Measure side lengths with a ruler to find area. Find area of rectangles by multiplying side lengths. Find a missing side length of a rectangle when given the other side length and area.