Wordpress - Override default url for author pages?

You can add this in your functions, and it will rewrite the slug from default "author" to "classroom",

function new_author_base() {
    global $wp_rewrite;
    $author_slug = 'classroom';
    $wp_rewrite->author_base = $author_slug;
}
add_action('init', 'new_author_base');

hope it helps you

You might wish to try.. http://wordpress.org/extend/plugins/custom-author-base/

Hope that helps.. ;)