Hi Oli,

I have read that also about reading early and later math ability but I do not recall where I read that. I went looking, didn't find anything whatsoever to back that up, but did find a study theorizing that ability to retell a story at age 3-4 predicts math ability two years later. Specifically the ability to relate the different perspectives of different characters and link events in a story. Vocabulary wasn't related.

http://www.arts.uwaterloo.ca/~doneill/papers/Storytelling%20and%20math.pdf

Polly