Stroke the wire with the magnet, picking up the magnet between each stroke, so that the magnet is only touching the wire in only one direction.
Push the wire through the styrofoam.
Float the styrofoam on the water in the tray.
The wire should orient along a north-south direction, as it is attracted to the earth's magnetic field. (A permanent magnet with N and S marked on it is needed to determine which end of the needle points north).