Oran uses a ball, a bar magnet, and a compass to create a model of earth’s magnetic field. how could he best use these materials? he could glue the compass to the ball so the needle points to the top of the ball, and move the bar magnet to show how the compass direction changes. he could glue the compass to the ball so the needle points to the bottom of the ball, and move the bar magnet to show how the compass direction changes. he could place the bar magnet in the ball so that the north pole of the magnet is at the top of the ball and the compass needle points to it. he could place the bar magnet in the ball so that the south pole of the magnet is at the top of the ball and the compass needle points to it.