Comparing fractions (age 9+)
Compare and order fractions with different numerators and denominators by creating common denominators/numerators or comparing to a benchmark such as 1/2; justify conclusions with visual models
What a learner can do afterwards
- Compare 3/8 and 5/12 by finding a common denominator of 24
- Order 2/3, 3/5, and 7/10 from smallest to largest
- Use the benchmark 1/2 to decide that 5/8 > 3/7
The lesson
You already know how to compare fractions that share the same bottom number, or that sit near one-half. Now you'll compare fractions where the top and bottom numbers are both different, like 3/8 and 5/12. The trick is to rewrite both fractions with a common denominator, or check each one against the benchmark 1/2.
Compare 3/8 and 5/12. Both 8 and 12 divide evenly into 24, so rewrite each fraction with 24 as the denominator: 3/8 becomes 9/24, and 5/12 becomes 10/24. Since 10/24 is more than 9/24, 5/12 is the bigger fraction.
If you're not sure, draw a quick picture or check both fractions against one-half. If one fraction is under 1/2 and the other is over 1/2, you already know which is bigger.
To compare fractions with different tops and bottoms, make a common denominator or check each one against one-half.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.