Your next question is probably, so why are your children AT this school. That has a long, involved answer involving the "least worst" option analysis and I won't bore you with it. However, they are at the elementary school and I am trying to get the leadership to face the merit scholar (and related college admission, as polarbear rightly points out) issue and not simply define it as a non-issue.
SAT scores and other measures of intelligence are not affected much by the variation of quality in schools within the U.S. or by other variables that parents can control, so I don't think your children will be harmed by attending a high school with few National Merit Scholars.
