Math oddities

Yesterday, Erika could neither remember what 6 + 3 was, nor could she think of a way to come up with the answer.

This morning, Erika had no trouble solving any problem within 10, including missing addend problems and subtraction problems. In response to problems like this:

4 + ? = 9

She was saying things like, "well, it can't be 4 + 4, because that's 8, so it must be 4 + 5." In response to problems like this:

7 - 3 = ?

She would say, "I know that 3 + 4 is 7, so the answer must be 4."

She was on a total roll.

The only problem she did have trouble with was this one:

8 - 3 = ?

She answered 11, because she hadn't noticed that it was a subtraction problem.

Learning is weird.