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Folded napkin — the angle at the crease
During a busy dinner service, a waiter folds a rectangular paper napkin along a diagonal crease running from its top-left corner to its bottom-right corner, as shown. At the bottom-right corner, the angle between the right-hand edge of the napkin and the folded-over edge is 24°, and x is the angle between that folded edge and the crease. Find angle x.
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65 worked examples are free without a code, two from every pattern. No account, either way.
The pattern behind it: Seeing it move
Work out where the pieces land after a fold, cut or stack.
In this one. A fold is a reflection, so the crease bisects the angle between an edge and its folded image.
How to spot it
Words like 'folded', 'cut along the dotted line' or 'stacked' appear beside a shape, and the question asks for a length or angle that only makes sense once the pieces are in their new positions.
Common mistake
Children try to calculate the answer before working out where the pieces actually end up, skipping the visualisation step that the whole question depends on.
Try one like it
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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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