Answer key

The answer, and what a wrong answer means.

#	Problem	Answer	If they wrote…
1	9 + 3	12	13 rounding to add, then forgetting to adjust
2	9 + 4	13	14 rounding to add, then forgetting to adjust
3	3 + 1	4	no pattern to catch here
4	5 + 5	10	no pattern to catch here
5	7 + 6	13	no pattern to catch here
6	9 + 5	14	15 rounding to add, then forgetting to adjust
7	9 + 1	10	no pattern to catch here
8	4 + 3	7	no pattern to catch here
9	8 + 4	12	14 rounding to add, then forgetting to adjust
10	2 + 2	4	no pattern to catch here
11	4 + 9	13	14 rounding to add, then forgetting to adjust
12	8 + 6	14	16 rounding to add, then forgetting to adjust
13	4 + 8	12	14 rounding to add, then forgetting to adjust
14	7 + 8	15	no pattern to catch here
15	8 + 8	16	no pattern to catch here
16	7 + 1	8	no pattern to catch here
17	3 + 4	7	no pattern to catch here
18	4 + 7	11	no pattern to catch here
19	9 + 9	18	no pattern to catch here
20	9 + 2	11	12 rounding to add, then forgetting to adjust

Reading the wrong answers

One wrong answer is a slip. The same pattern on three or more problems is a rule your child is following, and it has a name and a fix. Problems marked "no pattern to catch" are the plain ones; a child who gets only those right is telling you something too.

Reading the wrong answers

Rounding to add, then forgetting to adjust 8 of 20 problems