Curated OER
Area of Regular Quadrilaterals
Can your class calculate the area of a regular quadrilateral? They can now, with this handy presentation which provides an explanation, the formula, and examples of finding the area of a regular 2-D shape.
Mathigon
Mathigon: Geometry: Polygons and Polyhedra: Quadrilaterals
This lesson focuses on quadrilaterals which can fall into multiple categories based on the number of sides and the angles.