The pattern
Constant difference
The gap between the two amounts never changes.
Ages, or two amounts with the same amount added to each, keep the same gap between them, because nothing passes from one person to the other. Draw the before and the after so the gap is the same number of shares in both. The gap is the one thing that survives every change.
How to spot it
Both amounts go up or down by the same amount. Ages are the common case, because the same number of years passes for both people.
Common mistake
Children treat the gap as fixed when only one person changed, forgetting that adding to one person alone moves the gap by exactly that amount.
1 worked solution
Standard
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The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
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