Classifying quadrilaterals - seven types of quadrilaterals and their family tree
Do you know the seven types of quadrilaterals? We look at the quadrilaterals "family tree", first with only four types of quadrilaterals (to keep it simple), and then we add the rest. The completed family includes the kite, the trapezoid, the parallelogram, the rhombus, the rectangle, and the square. A scalene quadrilateral would form its own branch, so is not included.
The family tree helps us to solve questions such as if a parallelogram is also a kite, or if a rectangle is trapezoid.
This family tree uses this definition for a trapezoid: a trapezoid is a quadrilateral with AT LEAST one pair of parallel sides. That way, it can have "children" in the family tree — the parallelogram, the rhombus, the rectangle, and the square, which all also have at least one pair of parallel sides (in reality 2, but they fit the definition).
See also
Classify triangles — video lesson
Math Mammoth Geometry 1 — a self-teaching worktext with explanations & exercises (grades 4-5)