Geometry
Confusing Volume and Surface Area
Students use a volume formula when the problem asks for surface area, or a surface area formula when it asks for volume.
Quick check
Why students make it
Both measurements describe a 3D solid, so students mix up the space inside with the covering on the outside. The same dimensions are often used in both formulas, which makes the wrong formula feel familiar.
The rule done right
Volume measures the space inside a solid and uses cubic units, such as . Surface area measures the total area of all outside faces and uses square units, such as .
Related resources
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Geometry, Lateral vs Total Surface Area Infographic -
Geometry, Units of Area and Volume Infographic -
Volume & Surface Area Infographic -
Geometry, Surface Area of a Prism Infographic -
Geometry, Volume of a Prism Infographic - 3D Shapes & Nets Cheat Sheet
- Area, Surface Area & Volume Cheat Sheet
- Surface Area & Volume Formulas Cheat Sheet
- Surface Area of Cylinders Cones and Spheres Worked Examples Cheat Sheet
- Volume Formulas Quick Card Cheat Sheet
- Math, Volume and Surface Area Worksheet
- Surface Area of 3D Figures Worksheet
- Surface Area of Rectangular Prisms Worksheet
- Surface Area Net Builder Tool
- 3D Shape Calculator Tool
- Cross-Sections of 3D Solids Explorer Tool
- Area & Perimeter Explorer Tool