public function set_columns() {
		return array(
			'id'        => array(
				'title' => __( 'ID', 'lifterlms' ),
			),
			'name'      => array(
				'title' => __( 'Name', 'lifterlms' ),
			),
			'quiz'      => array(
				'title' => __( 'Quiz', 'lifterlms' ),
			),
			'grade'     => array(
				'title' => __( 'Grade', 'lifterlms' ),
			),
			'completed' => array(
				'title' => __( 'Completed', 'lifterlms' ),
			),
			'actions'   => array(
				'exportable' => false,
				'title'      => __( 'Actions', 'lifterlms' ),
			),
		);
	}