🧮 Adding Fractions - Unlike Denominators — Finding Common Denominators
Explore the Kelp Forest with Captain Coral!
Read the Passage First!
🔤 Words to Know
Unlike denominators — Fractions with different bottom numbers, like 1/3 and 1/4.
Common denominator — A shared bottom number that lets you add or subtract fractions.
Least common multiple — The smallest number that both denominators divide into evenly.
Captain Coral and Wanda were studying sea creatures in the sea otter habitat when they needed to combine measurements. One kelp strand grew 1/3 of a meter on Monday and 1/4 of a meter on Tuesday.
"I need to add 1/3 + 1/4, but the denominators are different!" said Captain Coral.
"Find a common denominator," said Wanda. "The least common multiple of 3 and 4 is 12."
"So I convert: 1/3 = 4/12 and 1/4 = 3/12. Now I can add: 4/12 + 3/12 = 7/12 of a meter!"
"When denominators are different, you must find equivalent fractions with the same denominator before adding," said Wanda.
Captain Coral tried another: "2/5 + 1/3. LCM of 5 and 3 is 15. Convert: 2/5 = 6/15, 1/3 = 5/15. Add: 6/15 + 5/15 = 11/15!"
"Always simplify your answer if possible," reminded Wanda. "And make sure the denominators match before you add the numerators."
Captain Coral felt confident. "Finding common denominators is like finding a common language — it lets different fractions communicate!"
🧠 Answer the Questions
Read carefully!
Why must you find a common denominator?
What is the LCM of 3 and 4?
1/3 + 1/4 = ?
2/5 + 1/3 = ?
What is a common denominator?
What are unlike denominators?
Convert 1/3 to twelfths.
What did Bob compare finding common denominators to?
When adding fractions, what do you add?
Should you simplify your answer?
3/8 + 1/8 = ?
What is the LCM of 6 and 4?
Where did the story take place?
What grew 1/3 meter on Monday?