combine plane shapes
Two triangles are joined as shown. What larger plane shape do they make?
Show the answerHide the answer
square
The pattern behind it: Seeing it move
Work out where the pieces land after a fold, cut or stack.
In this one. Small plane shapes can join without gaps to form a larger shape.
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
Standard combine plane shapes Two equal squares are joined as shown. What larger plane shape do they make?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.
A PDF, and a note when new solutions go up.