Divide by a Common Factor
Focus: Simplifying with Common Factors. Use the worked example and teaching sequence below to explain the reasoning before independent practice.
Use New Numbers to make another set. Choose Worksheet or Answer Key, then use the worksheet’s Print button.
Teaching Notes
Focus: Simplifying with Common Factors. Use the worked example and teaching sequence below to explain the reasoning before independent practice.
Before You Begin
- Find common factors.
Teaching Steps for Parents and Teachers
- Find a common factor of the numerator and denominator.
- Divide both by that factor.
- Continue until their only common factor is 1.
Worked Examples
Simplify 12/18.
- The greatest common factor of 12 and 18 is 6.
- 12 ÷ 6 = 2; 18 ÷ 6 = 3.
Answer: 2/3
Common Mistakes and How to Help
Divide both parts by the same factor.
Can the numerator and denominator be divided by another common factor greater than 1?
Questions to Check Understanding
- Can the numerator and denominator be divided by another common factor greater than 1?
- Which step explains your answer?
- Can you apply the same reasoning when the numbers change?
Practice Advice
Work through the example together. Ask the learner to explain the first two problems, then try three independently. Review the first incorrect step before assigning more practice.
Next Practice
- Use New Numbers to practice the same skill with different values.
- If the learner needs help, return to the example and model each step before trying again.