Khan Academy

Area of composite shapes (K-A)

Area of kites (K-A)

Area of trapezoids (K-A)

Challenge problems: perimeter & area (K-A)

Area of a triangle (K-A)

Finding area by rearranging parts (K-A)

Area of triangle proof (K-A)

Perimeter & area of composite shapes (K-A)

Creating rectangles with a given area 1 (K-A)

Creating rectangles with a given area 2 (K-A)

Intro to area and unit squares (K-A)

Measuring area with partial unit squares (K-A)

Measuring rectangles with different unit squares (K-A)

Applying the metric system to perimeter (K-A)

Finding missing side length when given perimeter (K-A)

Finding perimeter when a side length is missing (K-A)

Perimeter & area (K-A)

Perimeter and unit conversion (K-A)

Perimeter of a shape (K-A)

Perimeter: introduction (K-A)

Rotating 2D shapes in 3D (K-A)

Slicing a rectangular pyramid (K-A)

Ways to cross-section a cube (K-A)

Heron's formula (K-A)

Proof of Heron's formula (1 of 2) (K-A)