Worksheet generator

1.B — 8KA-0119Find what is actually being asked

• AI halved the difference, as if the question asked how many Bo should hand over to make them equal.
• CI gave how many Bo has now rather than how many more he has than Ana.
• DI gave the number Bo started with, without doing anything.
• EI added the two amounts together instead of comparing them.

2.A — 12KA-0122Back-solve from the answer choices

• BI assumed a number with two different prime factors always has six factors.
• CI counted the factors of 16 as six by including a number twice.
• DI assumed a square number has six factors without listing them.
• EI counted the powers of 3 up to 27 and thought there were six of them.

3.C — 28KA-0123Eliminate impossible choices by bounding

• AI ruled out the square 6 by 6, forgetting that a square is a rectangle.
• BI did not think to try 4 by 9, so I judged this perimeter impossible.
• DI missed the 3 by 12 rectangle when listing the factor pairs.
• EI stopped listing factor pairs before reaching 2 by 18.

4.B — 7KA-0131Back-solve from the answer choices

• AI tested the first choice, got 13, and picked it anyway because it was close.
• CI added the 3 to 17 instead of subtracting it, then halved the 20 that gave me.
• DI subtracted 3 from 17 and gave that without halving it.
• EI added 3 to 17 instead of undoing the addition by subtracting it.

5.D — 21KA-0132Eliminate impossible choices by bounding

• AI did not try one five and four twos, so I judged this total impossible.
• BI missed the combination of two fives and three twos.
• CI stopped listing after two fives and never reached three fives and two twos.
• EI forgot the case where every coin is a five, which is allowed by the wording.