public function html() {
        global $OUTPUT;

        $options = $this->options;
        $selected = $this->selected;

        $context = array(
            'name' => $this->name,
            'value' => $this->selected,
            'tabindex' => 1,
            'disabled' => !empty($this->isdisabled),
            'options' => array_map(function($option) use ($options, $selected) {
                return [
                    'name' => $options[$option],
                    'value' => $option,
                    'selected' => $selected == $option
                ];
            }, array_keys($options))
        );

        return $OUTPUT->render_from_template('gradereport_singleview/dropdown_attribute', $context);
    }