Place a second dot where the needle points now. Continue to move the compass and make dots until you reach another point on the bar magnet or the edge of the paper. Connect the dots with a smooth curve. Repeat for other lines, spread out more or less evenly over the area. The N-seeking tip of a compass will point to the N pole of the Earth or the S end of a bar magnet.
Place arrowheads on each line.
Find and label an area where the two fields cancel, and explain their evidence for this cancelling. Post the field maps. 1. Make and discuss overhead transparencies of the geomagnetic field as seen from space, stretched by the solar wind. Ask for similarities to gravitational and electrical fields, as well as differences. For that special group that really needs some extra attention, be sure to tape an extra magnet to the bottom of their table before class.