TOPIC 7 · GRADE 4 FOUNDATION
Add and Subtract Like Denominators
Combine or remove equal-sized parts, including answers greater than one.
MA.4.FR.2.2BIG IDEA
When denominators match, the pieces have the same name and size, so add or subtract their counts while the denominator stays the same.
LEARN IT WITH A STORY
Combine equal-size measuring cups
A recipe uses 2/8 cup of one ingredient and 3/8 cup of another. Because every piece is an eighth, count 2 + 3 eighths to get 5/8 cup.
- 1Check that denominators match; the pieces must have the same size and name.
- 2Add or subtract the numerators to count those pieces.
- 3Keep the denominator because the piece size has not changed, then simplify if possible.
Draw and explain
Draw eighths to solve 7/8 − 3/8. Explain why the denominator stays 8.
FRACTION WORD BANK
Tap a word, then turn the card
Say the word aloud before revealing its meaning. Tap again to return to the word.
WATCH AND NOTICE
Adding fractions with like denominators | Khan Academy
Pause when a model appears. Name the whole, denominator, numerator, and fraction before the teacher explains it.
Open on YouTube ↗WHAT TO KNOW
- 3/8 + 4/8 means three eighths plus four eighths, or seven eighths.
- The denominator stays fixed because the size of each piece has not changed.
- A result such as 9/6 can regroup as 1 3/6.
WATCH OUT
Do not add denominators in like-denominator addition; eighths plus eighths are still eighths.
TRY IT
Combine two colored sets of equal-size pieces in one bar.