Answer key

The answer, and what a wrong answer means.

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