Answer key

The answer, and what a wrong answer means.

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