Worksheet generator

1.C — 16KA-0019Multi-step arithmetic word problems

• AI found what one child has left and gave that instead of the total for all four.
• BI divided 24 by 4 and then subtracted 2 twice, mixing up per-child steps with total steps.
• DI subtracted 2 pencils once from the whole pack instead of once from each of the four children.
• EI subtracted the 2 before sharing, so only one lot of 2 ever came out of the total.

2.C — 61KA-0030Arithmetic sequences and the nth term

• AI added the step 18 times, counting the gaps between terms one too few.
• BI multiplied the step of 3 by 20 and forgot that the first term is already in place.
• DI used a first term of 3 instead of 4 while adding 20 steps.
• EI added the step 20 times to the first term instead of 19 times.

3.D — 9KA-0046Counting by position (sliding window)

• AI cut the board into four separate 2 by 2 blocks instead of sliding the square one step at a time.
• BI counted the three sliding positions along the top and doubled them for two rows.
• CI counted the positions along the top row and down the left column and added them.
• EI counted the sixteen small squares on the board rather than the 2 by 2 squares.

4.C — 11KA-0066Means, and working backwards from a mean

• AI assumed the missing number must be the mean itself.
• BI averaged the three known numbers instead of working from the total.
• DI repeated one of the numbers already given rather than computing the missing one.
• EI used a total of 37 instead of 36, adding the mean in once too often.

5.B — 4KA-0069Inclusion–exclusion with two sets

• AI added 18 and 14 without removing the overlap, then subtracted from 30.
• CI subtracted the 6 who play both twice instead of once.
• DI subtracted only the footballers from the class and forgot the chess players entirely.
• EI found how many play at least one sport and gave that instead of how many play neither.

6.D — 24KA-0073Arrangements of a few objects

• AI counted the letters rather than their arrangements.
• BI multiplied 4 by 3 and stopped, forgetting the last two positions.
• CI used 4 choices for every position, as if letters could repeat.
• EI used 4 choices in each of four positions, which allows every letter to repeat.

7.D — 1200KA-0128Check units and re-read before bubbling

• AI worked entirely in metres and gave the answer in square metres.
• BI multiplied 30 by 0.4 without converting the metres to centimetres at all.
• CI converted 0.4 m to 4 cm rather than 40 cm.
• EI converted 0.4 m to 400 cm, moving the decimal point one place too far.

8.C — 4KA-0040The pigeonhole principle

• AI answered with the lucky case, where the first two socks happen to match.
• BI used the number of colours as my answer without adding one for the sock that must repeat.
• DI worked from the number of socks of each colour instead of the number of colours.
• EI took the whole drawer, guaranteeing a pair but far more socks than are needed.

9.D — No, because the number of moves is oddKA-0097Parity arguments

• AI assumed enough moves can undo anything, without asking what each move preserves.
• BI tried a few sequences that nearly worked and assumed a better choice would finish the job.
• CI reached for the number of items rather than for what a single swap actually changes.
• EI thought the choice of swaps could change the outcome, when every swap has the same effect.

10.C — 14KA-0139Dice and cube face relationships

• AI subtracted only the top face from 21, forgetting the hidden bottom face as well.
• BI guessed four middling numbers and added them without using the total of all six faces.
• DI subtracted only the bottom face of 4 from the total of 21.
• EI added the four largest numbers on the die rather than the four that are actually at the sides.