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Mrs Tan used of her flour to bake a cake and of the remainder for cookies. What fraction of the flour was left?
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65 worked examples are free without a code, two from every pattern. No account, either way.
The second fraction is of one piece, not of the whole.
In this one. The second fraction bites into the remainder, not the whole — so 1/4 of the remainder is 1/4 of 1/3 = 1/12, and what survives is 3/4 of that third. (The trap: 1/3 − 1/4 = 1/12. That subtracts a quarter of the whole, which is not what happened.)
A second fraction arrives after the first and is attached to a piece rather than to the whole — 'of the remainder', 'of what was left', or 'of the ones that were red'.
Children take the second fraction of the original total instead of the piece it was named against, which makes the amount come out too big.
Worked examples of all 33 patterns and skills, in a booklet you can print.