Write the addition or subtraction the story needs and solve it with a common denominator. Then estimate: 1/2 + 3/5 is a bit more than 1, so 11/10 makes sense.
benchmarkan easy number to compare with, like ½ or 1
estimatea close guess
reasonablemakes sense for the story
common denominatora bottom number both fractions share
Watch for: Adding the tops and the bottoms, as in 2/5 + 1/2 = 3/7. Skipping the check: a sum can't be smaller than one of the fractions added. Adding when the story asks how much is left.
At home: Ask for a guess before working it out: is 3/4 + 1/2 more or less than 1? Then solve it together and see if the guess held.
Sample sheet and answer key
Luna's Space Adventure
Grade 5 · Fraction story problems · 5.NF.A.2
NameDate
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
Story problems
Solve, then check: is the answer more or less than ½? than 1?
Luna walked 1/8 mile and Nova walked 1/3 mile. How far did they walk altogether?
Nova walked 1/2 mile and Orion walked 2/3 mile. How far did they walk altogether?
Max walked 1/4 mile and Luna walked 1/5 mile. How far did they walk altogether?
Luna had 2/3 of a pizza and ate 3/5 of a pizza. How much pizza is left?
Nova walked 3/4 mile and Max walked 1/3 mile. How far did they walk altogether?
Max walked 1/4 mile and Zed walked 2/3 mile. How far did they walk altogether?
Does it make sense?
Use ½ and 1 to decide, without working it out.
2/5 + 1/2 is…less than 1more than 1
3/4 + 4/5 is…less than 1more than 1
Sam says 2/5 + 1/2 = 3/7. Is that reasonable?yesno
Sheet
Luna's Space Adventure
Grade 5 · Fraction story problems · 5.NF.A.2
Answer key
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
Story problems
Solve, then check: is the answer more or less than ½? than 1?
Luna walked 1/8 mile and Nova walked 1/3 mile. How far did they walk altogether?11/24
Nova walked 1/2 mile and Orion walked 2/3 mile. How far did they walk altogether?7/6
Max walked 1/4 mile and Luna walked 1/5 mile. How far did they walk altogether?9/20
Luna had 2/3 of a pizza and ate 3/5 of a pizza. How much pizza is left?1/15
Nova walked 3/4 mile and Max walked 1/3 mile. How far did they walk altogether?13/12
Max walked 1/4 mile and Zed walked 2/3 mile. How far did they walk altogether?11/12
Does it make sense?
Use ½ and 1 to decide, without working it out.
2/5 + 1/2 is…less than 1more than 1
3/4 + 4/5 is…less than 1more than 1
Sam says 2/5 + 1/2 = 3/7. Is that reasonable?yesno
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.
