Unlocking the Cube: Finding Dimensions from Volume
Lesson Description
Video Resource
Dimensions of a cube from its volume | Numbers and operations | 8th grade | Khan Academy
Khan Academy
Key Concepts
- Volume of a cube
- Cube roots
- Prime factorization
Learning Objectives
- Students will be able to calculate the side length of a cube given its volume.
- Students will be able to use prime factorization to find cube roots.
- Students will be able to relate volume to the dimensions of a cube.
Educator Instructions
- Introduction (5 mins)
Begin by reviewing the concept of volume, specifically the formula for the volume of a cube (V = s³). Briefly discuss perfect cubes and the concept of cube roots as the inverse operation of cubing a number. - Video Viewing (10 mins)
Watch the Khan Academy video 'Dimensions of a cube from its volume'. Encourage students to take notes on the presenter's method for finding the side length of a cube, including the use of prime factorization. - Guided Practice (15 mins)
Work through example problems similar to the one in the video. Start with simpler examples (e.g., volume = 27 cubic units) and gradually increase the complexity. Emphasize the steps involved: 1) set up the equation, 2) find the cube root, 3) simplify the cube root using prime factorization if necessary. - Independent Practice (15 mins)
Assign practice problems for students to solve independently. Circulate to provide assistance and answer questions. Encourage students to show their work and explain their reasoning. - Wrap-up and Assessment (5 mins)
Review key concepts and address any remaining questions. Administer a short quiz to assess understanding.
Interactive Exercises
- Cube Root Challenge
Provide students with a list of volumes and challenge them to find the corresponding side lengths. Include both perfect cubes and non-perfect cubes to encourage the use of prime factorization. - Visual Representation
Use physical cubes or a digital model to illustrate the relationship between volume and side length. Allow students to manipulate the cubes and visualize the concept.
Discussion Questions
- What is the relationship between the side length of a cube and its volume?
- How can prime factorization help us find cube roots?
- Can you think of real-world scenarios where you might need to calculate the dimensions of a cube given its volume?
Skills Developed
- Problem-solving
- Algebraic reasoning
- Critical thinking
Multiple Choice Questions
Question 1:
The volume of a cube is 64 cubic cm. What is the length of one side?
Correct Answer: 4 cm
Question 2:
What is the cube root of 125?
Correct Answer: 5
Question 3:
The volume of a cube is represented by the equation V = s³, where s is the side length. If V = 216, what is s?
Correct Answer: 6
Question 4:
Which of the following is a perfect cube?
Correct Answer: 27
Question 5:
What is the prime factorization of 8?
Correct Answer: 2 x 2 x 2
Question 6:
If the side length of a cube is 3 cm, what is its volume?
Correct Answer: 27 cubic cm
Question 7:
Which of the following represents 'x cubed'?
Correct Answer: x * x * x
Question 8:
What is the cube root of 1?
Correct Answer: 1
Question 9:
A cube has a volume of 1000 cubic meters. What is the measure of one side?
Correct Answer: 10 meters
Question 10:
The side length of a cube is represented by 'a'. What expression represents the volume of the cube?
Correct Answer: a³
Fill in the Blank Questions
Question 1:
The volume of a cube is found by cubing the length of its ____.
Correct Answer: side
Question 2:
The cube root of 8 is ____.
Correct Answer: 2
Question 3:
If V = s³, then s = the ____ root of V.
Correct Answer: cube
Question 4:
A perfect cube is a number that can be obtained by cubing a(n) ____ number.
Correct Answer: integer
Question 5:
Prime ____ is a method to break down a number into its prime factors.
Correct Answer: factorization
Question 6:
The cube root of 27 is ____.
Correct Answer: 3
Question 7:
A cube with sides of length 5 has a volume of _____.
Correct Answer: 125
Question 8:
If a cube has a volume of 1,728 cubic meters, each side measures _____ meters.
Correct Answer: 12
Question 9:
x * x * x can be written as x to the ____ power.
Correct Answer: third
Question 10:
Finding the side length of a cube when you know its volume involves calculating the ____ root.
Correct Answer: cube
Educational Standards
Teaching Materials
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