A square with side length 1 unit, called "a unit square," is said to have "one square unit" of area, and can be used to measure area.3.MD.C.5.B
A plane figure which can be covered without gaps or overlaps by n unit squares is said to have an area of n square units.
Compose two-dimensional shapes (rectangles, squares, trapezoids, triangles, half-circles, and quarter-circles) or three-dimensional shapes (cubes, right rectangular prisms, right circular cones, and right circular cylinders) to create a composite shape, and compose new shapes from the composite shape.
Measure areas by counting unit squares (square cm, square m, square in, square ft, and improvised units).
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.
Recognize volume as an attribute of solid figures and understand concepts of volume measurement.