Area of complex figures is a difficult concept - This is broken down into 3 lessons (and activities) step-by-step that will help students understand it in a more relative and concrete way.
Common Core Standards:
3.MD.C.7d Recognize area as additive. Find areas of rectilinear figures by decomposing
them into non-overlapping rectangles and adding the areas of the non-overlapping parts.
applying this technique to solve real world problems.
3.MD.C.7a Find the area of a rectangle with whole-number side lengths by tiling it, and
show that the area is the same as would be found by multiplying the side lengths.