Activities include exploring and discussing many shapes of rectangles, all at various orientations, including both typical ones but also "long and skinny ones" and even…squares as "special rectangles" that happen to have all our sides the same length. Discuss that the defining attribute of rectangles are right angles (rect-angles!).

Practice-based Research: All squares are rectangles because rectangles can be defined as shapes with pairs of parallel sides that are equal in length with all right angles (not “two long sides and two short sides”). However, all rectangles are not squares—only those with all four sides of equal length are squares. Avoid telling children "that's a square, not a rectangle," instead saying, "Good, that's a special rectangle with all sides equal length!  What do we call this special rectangle?" (A square.)

Rectangles are found nearly everywhere—windows, doors, photo frames, boards, light fixtures, floors, walls, and ceilings. Show and discuss examples of these with children.