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Painted block — Ravi cuts it into cubes
Ravi had a rectangular block of wood 10 cm by 5 cm by 4 cm. He painted all the faces of the block.
- (a) What is the total painted area?
- (b) Ravi cut the block into 1-cm cubes. How many of these cubes have (i) none of the faces painted? (ii) 2 of the faces painted?
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The pattern behind it: Seeing it move
Work out where the pieces land after a fold, cut or stack.
In this one. A small cube is painted on exactly the block faces it touches — so "0 faces" means strip a 1-cm skin off all six sides and count what is left, and "2 faces" means it lies on an edge but is not a corner.
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
Challenging Canvas — cut into a square and eight triangles Ravi has a square piece of canvas of side 31 cm. He cuts along the dotted lines to get one small square of area 289 cm² and 8 iden…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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