Fifth Grade · Math · week 12

Add unlike fractions

Add fractions with unlike denominators by finding a common denominator, adding numerators, and simplifying the result.

Now that you can find common denominators, adding unlike fractions is three moves: rewrite both fractions with the common denominator, add the numerators, and keep the denominator the same.

Always check whether the answer can be simplified to an equivalent fraction in simplest form.

📋 For the teacher
Teach it (10–15 min):
  • Walk through the three moves every time, out loud, in the same order: common denominator, add the tops, simplify.
  • Keep a small multiples chart handy so finding common denominators does not stall the whole problem.
  • Always ask "can this reduce?" as the very last step -- many answers do simplify.
  • Mix problems whose answer is already simplest with ones that need reducing, so neither assumption sticks.
Talk about it:
  • What are the three steps for adding unlike fractions?
  • How do you know when a fraction answer needs to be simplified?
  • Why does the denominator stay the same after you add the numerators?

Mastery looks like: They can add two unlike fractions by finding a common denominator, adding numerators, and simplifying the result.

Common stumbles: Adding the denominators together along with the numerators; forgetting to simplify a reducible answer.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

FractionsSlice bars and circles into equal parts and compare them.try →AdditionSee groups combine — with counters, blocks, and the number line.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
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