Math
Confusing Area and Perimeter
Students use the area formula when they need the perimeter, or use the perimeter formula when they need the area.
Quick check
Why students make it
Both measurements describe a shape, so students may treat them as the same kind of answer. The words around and inside get mixed up, especially when both use the same side lengths.
The rule done right
Perimeter is the distance around a shape, so add all side lengths. Area is the amount of space inside a shape, so for a rectangle use .
Related resources
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Math, Area and Perimeter Basics Infographic -
Geometry, Perimeter is the distance around the edge Infographic -
Area vs Perimeter Infographic -
Geometry, Perimeter of Polygons Infographic -
Geometry, Area of a Rectangle and Square Infographic - Perimeter is the distance around the edge Memory Aid Cheat Sheet
- Area & Perimeter Reference Cheat Sheet
- Polygons & Quadrilaterals Cheat Sheet
- Quadrilaterals Reference Cheat Sheet
- Triangles Cheat Sheet
- Geometry, Perimeter is the Distance Around the Edge Practice Worksheet
- Math, Area and Perimeter Worksheet
- Area and Perimeter of Rectangles Worksheet
- Measuring Perimeter with a Ruler Worksheet
- Area, Counting Square Units Worksheet
- Area Tiles & Perimeter Paths Tool
- Area & Perimeter Explorer Tool
- Polygon Properties Calculator Tool
- Area & Perimeter Design Challenge Lab
- Garden Area & Perimeter Lab Lab
- Measurement Detectives Lab Lab