Find the Wrong Number on the Piece

Six fully printed puzzle pieces sit on this 1st grade page — a plus, two L shapes, a 3-by-3 square and two T shapes — and every one of them contains a single mistake. On the sheet shown the plus reads 39, 84, 49, 50, 59, and 84 sits where 48 belongs; the square runs 2, 3, 4, 12, 13, 14, 22, 23, 33, and the last cell should be 24. A dashed box waits beside each piece. The child finds the number that does not fit the chart, circles it, and writes the right number in the box. There are no clean pieces; every piece has exactly one error.

Checking is a different act from filling. On the base page the child produces numbers; here they have to read six that are already there and decide which one breaks the pattern, which means testing each cell against its neighbours — is this 1 more than the cell to its left, is it 10 more than the cell above. The errors are the ones children actually make: digits swapped, a 10 written where a 1 belongs, a column jumped. Because the rest of the piece is right, the wrong cell is provable from the cells around it, and a child who circles the wrong one can be shown why.

One sheet, six circles and six corrections. This is the error-hunt face of the hundreds-chart-puzzles family and the one to give after the base fill-in-the-numbers page, when children make the moves confidently and need to start checking them. The where-does-the-piece-go page uses the same kind of printed pieces but asks for their place on an empty chart.