3.MD.C.6

Measure areas by counting unit squares (square cm, square m, square in, square ft, and improvised units).

Find area of composite rectangles (rectilinear figures) by counting unit squares. Students should be given a shape with gridlines overlayed. This lesson helps students see that area applies to more than just rectangles. Conclude by giving your students this challenge, then this one. The first puzzles is quite easy, the second quite difficult! Students should make sure the figures will have the same area before moving pieces around.