Construction
Construction puzzles treat each row as an equation: the first two cells are 'added together' to produce the third. In the simplest version this is a straightforward union — every piece present in either of the first two cells appears in the result. Harder versions introduce an XOR-style twist: pieces that appear in both of the first two cells cancel out and disappear, so only the pieces unique to one cell survive into the third.
The reliable approach is to treat each cell as a set of parts (not a single shape) and mentally combine the sets for the bottom row, then compare that combination against the answer options. Watch carefully for whether the puzzle uses simple union or the cancel-out variant — the two look similar until you check a cell where the same piece appears in both source cells.
How to spot it
- •Break each cell down into its individual pieces before trying to combine them.
- •Check one confirmed row first to determine whether the puzzle uses plain union or the cancel-out (XOR) variant.
- •If a piece appears in both source cells and the pattern is XOR-style, it should be absent from the result — a common trap answer includes it anyway.
- •Build the correct combination yourself before looking at the options, so you're not swayed by a plausible-looking distractor.