This is an amazingly provincial comment and it does not reflect well upon you.

Rather than assuming malice in your comment, however, I would gently suggest that it would be rather difficult for someone passed from grade to grade without basic functional literacy to ace such a test. Or, for a sneakier, harder to quantify example, there are "standardized" tests in circulation (and I was exposed to some of them in middle and high school) where certain cultural information was implicitly demanded. Probably not a problem for middle-class suburban kids, but unlikely to be appropriate for underprivileged very-rural kids (of which the testing area had many).

A narrow worldview isn't something to be ashamed of, but it is something to recognize and compensate for when making statements like yours.