I am doubtful that those fraction flashcards would be beneficial at any age.
Most ND kids can easily grasp, by 5-6, that 3/4 of a pie, means to count 3 out of the total 4 equal parts. I am sure my 3yo could master the point of those cards in 5min.
I am clueless as to why they would say 8 and up. Most fractions, are taught in grades 3-5 are not taught with "pie pictures" but on a fraction table and shift heavily into word problems.
I would worry that a child who has been heavily drilled with fraction flashcards alone, may develop a false sense of mastery, and have problems shifting into the deeper concept of fractions.
