CK-12 Foundation
Area and Perimeter of Rectangles: Lesson
Around and in—take a different look at rectangles. A portion of a basic geometry playlist discusses the area and perimeters of rectangles. Using the formulas, the presentation works perimeter and area examples with rectangles and squares.
Khan Academy
Khan Academy: Intro to Unit and Area Squares
Sal finds area of a rectangle with different sized units. [3:43]
Khan Academy
Khan Academy: Transitioning From Unit Squares to Area Formula
Conceptualize what area is by calculating the area of a rectangle by using unit squares and the area formula. [3:21]