This should a warning about how much our society is piling on the schools. Health Education is one thing, but evaluation of body type in a child just adds the hassles that the schools have to deal with in addition to testing and NCLB.
Classrooms used to a more fun, creative places, with a lot of leeway to accomodate parents and the latest teaching techniques. Now they are testing centers, and palaces to politically correct micromanagement.
This isn’t anything new. I remember my older brother had “obesity” marked on his report card in grade school.
BMI is probably a step in the right direction. (Assuming you think this is the purview of public schools) Weight tables are deceptive, because muscle weighs more than adipose tissue. Very buff, muscle-bound weightlifters bust all sorts of standard “you should weigh ___lbs to be healthy.”