well in theory it could make you taller, I don't know if I have seen a document case of weight training increasing the height of kids, but it would be an interesting study, you would have to use all of the under height kids in a larger school divide them into groups and then go from there, now that sounds like a basic starting point for someones master's thesis...
now as for lifeguard's statement.. most HS teachers do only answer based on the age of the student but I know I always attempt to qualify my answers to make sure that if there is an exception they know about it.. just so they don't look like an ass if they repeat it word for word.