Students will learn that area has a unit of measure. For example, we can measure in square inches, square feet, etc. Students will learn how to find the area of composite rectangles (rectilinear figures) by counting unit squares, noting their units of measure.

Measuring rectangles with different unit squares by Khan Academy

Find area by counting unit squares by Khan Academy

Next, give your students these challenges:

- Cover the Camel by NRICH
- Two Numbers Under the Microscope by NRICH

Conclude by leading this investigation:

Tree Kangaroo Hopscotch (skip counting)

by MathPickle

3.MD.C.5: Recognize area as an attribute of plane figures and understand concepts of area measurement.