Why does my child think 2/3 ÷ 1/2 = 1/3?
Your child divides fractions by multiplying straight across, such as 2/3 ÷ 1/2 = 1/3 instead of 4/3.
Why children do it
Multiplying fractions straight across works, so dividing straight across seems as if it should too. But dividing asks how many of one thing fit into another: how many halves fit into two thirds? More than one, so the answer must be bigger than 2/3. Turning the second fraction over and multiplying gives 4/3.
How to help at home
Dividing by a fraction is multiplying by it turned over: dividing by 1/2 is the same as multiplying by 2.
The right way
Calculate: (3/4) / (1/2)
- 3/4 × 2/1Turn the second fraction upside down and multiply.
- 6/4Multiply the tops and the bottoms.
- 3/2Simplify: divide the top and the bottom by 2.
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