public function col_scale($row) {
        global $DB;

        if (empty($this->scale)) {
            $dbparams = array('id' => -($this->assignment->get_instance()->grade));
            $this->scale = $DB->get_record('scale', $dbparams);
        }

        if (!empty($this->scale->scale)) {
            return implode("\n", explode(',', $this->scale->scale));
        }
        return '';
    }