Dividing fractions (unit fractions)
Interpret and compute division of a unit fraction by a non-zero whole number (e.g. 1/3 ÷ 4 = 1/12); use visual models and the relationship between multiplication and division to explain the result
What a learner can do afterwards
- Compute (1/3) ÷ 4 = 1/12 and explain using a visual model of splitting 1/3 into 4 equal parts
- Create a story context for (1/6) ÷ 3 and solve it
- Verify (1/3) ÷ 4 = 1/12 by showing (1/12) × 4 = 1/3
The lesson
Dividing a fraction by a whole number splits an already-small piece into even smaller equal pieces. If you have 1/3 of a bag of rice and share it evenly among 4 people, each person gets less than 1/3.
To work out 1/3 ÷ 4, cut the shaded third into 4 equal strips. The whole bar is now cut into 3 × 4 = 12 equal parts, and only 1 of those parts is shaded. So 1/3 ÷ 4 = 1/12.
The shortcut: to divide a unit fraction by a whole number, multiply the denominator by that whole number. The numerator stays 1. Check your answer by multiplying it back: 1/12 × 4 = 1/3.
Dividing a fraction by a whole number splits it into more, smaller equal pieces, so the answer is always smaller than what you started with.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.