Answer key

The answer, and what a wrong answer means.

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