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Adding & Subtracting Fractions Song
In a future time, when AI robots have taken over running pizzerias on a planet orbiting Alpha Centauri, the robot Zigon takes orders and then adds and subtracts fractions before the Pizzamatic-5000 serves up large pepperoni and cheese pizzas for its alien visitors! Adding Fractions has never been so stellar or astral.
This is how the least common multiple’s found:
write a list of each denominator’s multiples down;
the smallest number you can find in both of them
is the least common multiple (a.k.a. the LCM.)
The least common multiple can also be
called the least common denominator - or LCD.
It stays the same in the difference or the sum
when you subtract or add two fractions.
Three-sixths of a pizza minus one-fourth:
find the LCM, which is twelve, of course.
(Twelve is the least common denominator.)
Make equivalent fractions (six-twelfths and three-twelfths).
Then, do the subtraction: six minus three is three...
three-twelfths of a pizza at the pizzeria.
Find the least common multiple; that’s the first action.
Next, is finding equivalent fractions.
Then, do the addition or subtraction.
Simplify like an automatic reaction.
Two-fourths of a pizza plus one-fifth:
it smelled so good we had to give it a sniff.
The LCM was twenty (the new denominator).
We found equivalents quickly: ten-twentieths plus four-twentieths... fourteen-twentieths of a pizza at the pizzeria.
Five-sixths of a pizza minus one-third:
I knew the LCM was six, and have you heard?
It’s also called the least common denominator.
I found equivalent fractions (five-sixths and two-sixths).
Then, I did the subtraction: five minus two is three...
three-sixths of a pizza at the pizzeria.
This song targets TEKS and Common Core learning standards from both 4th Grade and 5th Grade. Look into the relevant standards here, or dig deeper into Subtracting Fractions here.
If you are interested in getting ideas on how to plan a robust standards-aligned telling time lesson, we recommend checking out Instructure's recommendations for common core standards 4.NF.4, and 5.NF.1 . These pages help break down standard language, lay out the grade-appropriate level of rigor for each concept, and offer a variety of suggestions for activities (lesson seeds) that help students achieve their learning targets
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