OER Commons
Oer Commons: Area of a Circle
Seventh graders will compare the formula for the area of a regular polygon to discover the formula for the area of a circle.
Shodor Education Foundation
Shodor Interactivate: Lesson: Area
This lesson plan helps students explore the mathematical concept of area and features resource links to further learning. CCSS.Math.Content.3.MD.C.7.a Find the area of a rectangle with whole-number side lengths by tiling it
CK-12 Foundation
Ck 12: Geometry: Perimeter and Area Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide looks at the definitions and units for perimeter, area, and circumference, and at the perimeter and area of different shapes, including regular...
Math Open Reference
Math Open Reference: Equilateral Triangle
Learn about equilateral triangles with this helpful reference tool. Provides a detailed definition, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
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.