This is a list of the kinds of quadrilaterals that I remember from years ago. If I've forgotten one, please kindly refresh my memory.

Definitions:

• Quadrilateral: any four-sided figure
• Trapezium: a quadrilateral with NO parallel sides
• Trapezoid (old definition): a quadrilateral with exactly TWO sides parallel to each other
  Trapezoid (new definition): a quadrilateral with at least one pair of parallel sides
• Parallelogram: a quadrilateral with all four sides parallel (each side to its opposite)
• Rectangle: a parallelogram with all angles exactly equal to 90 degrees (right angles)
• Square: a rectangle with all four sides equal in length.
• Rhombus: a parallelogram with four equal sides (with or without right angles)
• Rhomboid: a parallelogram with no right angles and with adjacent sides of unequal length
• Kite: a quadrilateral with two distinct pairs of consecutive sides congruent (think of old-fashioned paper kites with two unequal-but-perpendicular axes, the longer axis bisecting the shorter).

Note that some figures have more than one name. For example:

• All squares are rectangles, but not all rectangles are squares.

• All rectangles are parallelograms, but not all parallelograms are rectangles

• All squares are rhombuses, but not all rhombuses are squares.

• A rhombus (and also a square) are special types of kites.

• How many of these statements can you come up with?

How many names can you assign to each figure that you create?

Here are a few questions for you:

• Can you create a trapezium with exactly two right angles?

• Can you create a trapezoid with two horizontal sides, such that the upper side is NOT above the lower side?

• What challenges can you come up with for your friends?

*****

This material was written by John <Webmaster (at) Mazes.com> Knoderer (©'99). If your non-profit educational site would like to archive this material for free student use, permission is hereby granted. Please notify the author. Thank You