Objective: Students will notice that the strength of magnetic attraction depends on several variables.

Test different materials for their power to stop the magnet's "pull".

Suspend a horseshoe magnet, ends down. Tie a piece of thread to a paperclip and tape the free end to the desk. The thread should be long enough to leave about 1.5 cm between the paperclip and the magnet. Carefully pass thin sheets of different materials (cardboard, glass, tin, aluminum (baking sheet), steel (knife, spatula), wood, plastic, carpet, rubber, asphalt tile, ceramic tile) between the magnet and paperclip and watch the attraction of the paperclip to the magnet.