092. Volume of Rectangular Prisms

Learning Intentions

  • To understand what the volume of a three-dimensional object is
  • To know that common metric units for volume include cubic millimetres, cubic centimetres, cubic metres and cubic kilometres
  • To know what a rectangular prism (or cuboid) is
  • Solve the volume of a cube and other rectangular prisms

Pre-requisite Summary

  • Know that three-dimensional objects have length, width and height
  • Know that volume measures the amount of space inside a three-dimensional object
  • Know that volume is measured in cubic units such as , , and
  • Know that a cubic unit means a cube
  • Know that a rectangular prism has rectangular faces
  • Know that a cube is a special rectangular prism with all edges equal
  • Know how to multiply whole numbers and decimals
  • Know that the volume of a rectangular prism is found Use

Worked Examples

Worked Example 1

Decide whether each statement describes volume.

a) The amount of space inside a box

b) The distance around the edge of a shape

c) The amount of space a solid object takes up

Worked Example 2

Name the most suitable metric unit for the volume of each object.

a) A lunchbox

b) A shipping container

c) A tiny grain of sand

Worked Example 3

A rectangular prism has length , width and height . Find its volume.

Worked Example 4

A cube has side length . Find its volume.

Worked Example 5

A rectangular prism has dimensions , and . Find its volume.

Worked Example 6

A storage box is long, wide and high. Find its volume in cubic centimetres.

Problems

Problem 1

Decide whether each statement describes volume.

a) The amount of space inside a solid

b) The area of a flat surface

c) The space taken up by a 3D object

Problem 2

Name the most suitable metric unit for the volume of each object.

a) A classroom

b) A small dice

c) A very large mountain of rock

Problem 3

A rectangular prism has length , width and height . Find its volume.

092.p3.excalidraw.dark.svg

Problem 4

A cube has side length . Find its volume.

092.p4.excalidraw.dark.svg

Problem 5

A rectangular prism has dimensions , and . Find its volume.

092.p5.excalidraw.dark.svg

Problem 6

A fish tank is long, wide and high. Find its volume in cubic centimetres.

092.p6.excalidraw.dark.svg

Exercises

Understanding and Fluency

Exercise 1.

Decide whether each statement is about volume.

a) The amount of space inside a solid

b) The distance around a shape

c) The number of cubic units needed to fill a solid

Exercise 2.

Choose the most suitable metric unit for volume.

a) A tiny bead

b) A shoebox

c) A large building

Exercise 3.

Complete the statements.

a) Volume is measured in units

b) A rectangular prism is a -dimensional object

c) A cube is a special type of prism

Exercise 4.

Find the volume of each rectangular prism.

a)

b)

c)

092.e4.excalidraw.dark.svg

Exercise 5.

Find the volume of each cube.

a) Side length

b) Side length

c) Side length

092.e5.excalidraw.dark.svg

Exercise 6.

Find the volume of each rectangular prism.

a) Length , width , height

b) Length , width , height

c) Length , width , height

092.e6.excalidraw.dark.svg

Exercise 7.

Find the missing dimension.

a) , ,

b) , ,

c) , cube side length

092.e7.excalidraw.dark.svg

Exercise 8.

Decide whether each solid is a rectangular prism.

a) A cube

b) A cylinder

c) A box-shaped brick

Reasoning

Exercise 9.

Explain why volume is measured in cubic units rather than square units.

Exercise 10.

A student says the volume of a rectangular prism is found by adding its length, width and height. Explain why this is incorrect.

Exercise 11.

Explain why a cube can be found using the same volume rule as a rectangular prism.

Exercise 12.

A rectangular prism has dimensions , and . One student says the volume is and another says it is . Determine who is correct and explain why.

Problem-solving

Exercise 13.

A gift box is long, wide and high. Find its volume.

092.e13.excalidraw.dark.svg

Exercise 14.

A storage crate is shaped like a cube with side length . Find its volume.

092.e14.excalidraw.dark.svg

Exercise 15.

A fish tank is long, wide and high. Find its volume.

092.e15.excalidraw.dark.svg

Exercise 16.

A shipping container is long, wide and high. Find its volume.

092.e16.excalidraw.dark.svg

Exercise 17.

A brick has dimensions . How many cubic centimetres does it occupy?

092.e17.excalidraw.dark.svg

Exercise 18.

A cube-shaped container has volume . Find the length of one edge.

092.e18.excalidraw.dark.svg

Potential Misunderstandings

  • A student may confuse volume with area and think volume measures a flat surface
  • A student may confuse volume with perimeter and think volume is about the distance around an object
  • A student may Use square units instead of cubic units
  • A student may not Recognise that a cube is a special rectangular prism
  • A student may multiply only two dimensions instead of three
  • A student may add the dimensions instead of multiplying them
  • A student may omit the units or write incorrect units in the final answer
  • A student may think cubic units are only used for cubes, rather than for all volume measurements

Next: 093. Volume of Triangular Prisms