How a square can also be considered a rectangle as well as other shapes.

Every square is a rectangle, but not every rectangle is a square. A rectangle always has 4 right angles. So does a square, so that can be considered a rectangle. A rectangle can have sides of any length just as long as all four angles are right angles. A square however must have congruent sides. So not all rectangles are squares, only the rectangles with 4 congruent sides. In real life imagine that you are ordering flowers …

…a square? Yes. Is it possible to have a parallelogram that is not a rectangle? Yes, a rectangle has 4 right angles and all sides are parallel. however a parallelogram can not be considered a rectangle because it does not have 4 right angles even though the lines are all parallel. Is it possible to have a rectangle that is not a parallelogram? No, All rectangles are parallelograms, because the sides in a rectangle are always parallel.