I wouldn't worry about using cards if your children enjoy them; my ds did not really dig those so we don't have any lying around for dd to check out, but I think she would probably go for them. We do have some big dk number books that she likes. Progressively larger numbers of teddy bears, bugs, etc., nice dk photos to keep her interested.
Ds was more of an overnight changes type, dd seems pretty darn systematic. Maybe she's just verbalizing more of it.

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