Answer key

The answer, and what a wrong answer means.

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