Once upon a time there was an egg named Oscar. He woke up one morning, opened his door, looked up at the beautiful sun and said, “Ahhh, what a glorious day for a walk”.
Oscar set out to walk down the street. He got the end of the street and turned left. He went to the end of that street and turned left again. After walking some distance, he turned left again. He then walked for a while and turned left again, eventually ending up before his own front door.
In front of his own door, he thought, “I’ve gone in a complete circle!” but he immediately started thinking about the path he had taken, “If I were to draw my route on paper, I believe it would not be a circle at all, but would be a rectangle. In fact, it might even be a square.”
You see, a rectangle is a particular geometric shape with four parallel sides (pointing in the same direction) and four identical corners that are each a right angle. A square is a rectangle that also has four parallel sides and four corners that are right angles, but it’s sides are all the same length.
All squares are also rectangles but not all rectangles are squares. You see, rectangles may have two sides that are a different length than the other two.
So Oscar concluded that he probably traveled in a square, not a circle. Since he traveled in a square, he must have also travelled in a rectangle.
A Parallelogram is a lot like a rectangle. It has two sets of parallel sides, but it may or may not have four right angles for the corners. So all rectangles are parallelograms, but not all parallelograms are rectangles. Since all squares are rectangles, all squares must also be parallelograms.
So Oscar concluded that his journey was the shape of a square, rectangle, and parallelogram.
A Rhombus is a parallelogram that has four sides, each the same length, but the four corners are not necessarily right angles. Therefore, all rhombuses are parallelograms, but not all parallelograms are also rhombuses. All squares are also rhombuses, but not all rhombuses are squares. If a Rhombus is a square, it also a rectangle, but that’s beside the point. (And I apologize for throwing in that completely useless piece of information.)
So Oscar concluded that his path was a Square-Rhombus-Rectangle-Parallelogram, and he was quite pleased with himself.
A quadrilateral is any shape with four sides that are straight lines. The lines can be any willy-nilly length that they want and the corners can be any unpredictable angle. (You can guess by my tone that I don’t care much for quadrilaterals, because, like Oscar, I like things to be neat and orderly.) However, a quadrilateral could (but may not) have four sides that are the same length and could (but may not) have four corners that are right angles. Therefore, all squares, rhombuses, parallelograms and rectangles are also quadrilaterals, but not all quadrilaterals are any of those other things.
So Oscar concluded that his path was simultaneously a quadrilateral, parallelogram, rectangle, rhombus, and square. All in all, it was a very busy day for an egg, so Oscar decided it was time for bed. And so he went back in his flat, closed the door, and climbed right into bed.
The End