Gifted children( especially mathmatically gifted) learn fraction early, 3 or 4 years old.
The easiest way is divide a circle into a few parts, you can see it in year 2 book.
But if you do like to know what fraction mean, possibly has to wait after division.
When kids understand division, you can involve fraction---
like split 8 lego blocks into 4 groups, 1 group, means 1/4 is 2,
2 groups means, 2/4 is 2 of 2, which is 4...etc
My son understand half and quarter when he was three, by cutting food, now he is 4.3, can add and multiply fraction, but my suggestion, use objects instead of flash card
