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