With same-size pieces, add or subtract the number of pieces: 1/5 + 3/5 = 4/5, and the bottom stays. For mixed numbers, add the wholes and the fractions, then turn 3/3 into 1.
numeratorthe top number: how many parts
denominatorthe bottom number: the size of the parts
mixed numbera whole number and a fraction: 2 1/3
like denominatorsthe same bottom number
Watch for: Adding the bottoms too: 1/3 + 1/3 = 2/6. Leaving a mixed number like 6 3/3 instead of making it 7. Subtracting mixed numbers without trading a whole when the fraction is too small.
At home: Use a measuring cup: pour 1/4 cup of water, then 2/4 cup more, and check that it reaches 3/4.
Sample sheet and answer key
Luna's Space Adventure
Grade 4 · Adding fractions · 4.NF.B.3
NameDate
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
Same-size pieces
Add or subtract the numerators. The denominator stays.
210+510=810+810=812+912=412−212=12+12=25+15=
Mixed numbers
Add the wholes, add the fractions, then tidy up.
136+156=126+236=448+148=223+223=
Story time
Zed painted 3/6 of a fence and Nova painted 2/6. How much of the fence is painted?
Nova painted 5/8 of a fence and Zed painted 2/8. How much of the fence is painted?
Sheet
Luna's Space Adventure
Grade 4 · Adding fractions · 4.NF.B.3
Answer key
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
Same-size pieces
Add or subtract the numerators. The denominator stays.
Zed painted 3/6 of a fence and Nova painted 2/6. How much of the fence is painted?5/6
Nova painted 5/8 of a fence and Zed painted 2/8. How much of the fence is painted?7/8
Answer key
New problems every time, three levels (gentle, core and stretch), themes to pick from, a second page if you want one. Each sheet comes with an answer key and a one-page guide for grown-ups.
