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Find volume using unit cubes

Volume measures the three-dimensional space occupied by a solid, expressed as the number of unit cubes needed to fill it without gaps or overlaps. For rectangular prisms, learners interpret layers of congruent cubes and connect the count to V=×w×hV = \ell \times w \times h, distinguishing cubic units from square units and recognizing that changing any dimension changes the volume proportionally. This scope focuses on whole-unit-cube models and rectangular prisms, not fractional cubes or more advanced composite solids.

Detailed Explanation: Find volume using unit cubes

Volume tells how much space a solid takes up. We can find the volume of a rectangular prism by counting the unit cubes that fill it.

A unit cube has side lengths of 1 unit. Its volume is 1 cubic unit.

For a rectangular prism:

V=×w×hV=\ell \times w \times h

where \ell is length, ww is width, and hh is height.

Example: A rectangular prism is filled with cubes. It is 4 cubes long, 3 cubes wide, and 2 cubes high. What is its volume?

  1. Find the number of cubes in one bottom layer:
4×3=124 \times 3=12

There are 12 cubes in each layer.

  1. Count the layers:

There are 2 layers, so multiply by the height:

12×2=2412 \times 2=24

Or use the volume formula:

V=4×3×2=24V=4 \times 3 \times 2=24
  1. Include the correct units:
24 cubic units\boxed{24\text{ cubic units}}

The answer uses cubic units because we are measuring the space filled by three-dimensional cubes. Square units measure flat area, not volume.

Learn by doing: Find volume using unit cubes

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Volume of a Rectangular Prism - Count Blocks


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