Answer key

The answer, and what a wrong answer means.

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