Answer key

The answer, and what a wrong answer means.

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