Activity time: 20 minutes
Materials for Activity
- Cork and Needle Compass. A magnet for participants to share, and for each compass a plastic bowl or tub with a lid, a cork, a bit of modeling clay, a sewing needle, a toothpick, a marker, a sheet of paper larger than the plastic lid, glue or tape for attaching the paper to the lid, and water
- Super-Easy Supermagnet Compass. A rare earth magnet (preferably a neodymium disk magnet - see Resources), a tub of water, a foam meat tray, a knife (keep separate from the magnet), a permanent marker, and copies of Leader Resource 1, Super-Easy Supermagnet Compass, for each compass
Preparation for Activity
- The magnet you will need for each Super-Easy Supermagnet Compass - and, a good magnet to use for the Cork and Needle Compass - costs about $5. Decide which type of compass you will make, and how many, to determine the magnets you need to purchase. Do this well in advance, if you need to order "supermagnets" from an online vendor. (See Resources.)
- Photocopy Leader Resource 1, Super-Easy Supermagnet Compass, for each group that will make one of these compasses. The leader resource has detailed directions and pictures.
- Be aware of safety considerations: The magnet needed for the Super-Easy Supermagnet Copmass is very strong, and should not be used by fourth and fifth graders without supervision. On its own, it is perfectly safe, even for youngsters. It becomes hazardous when there are ferromagnetic materials nearby. Keep scissors somewhere else. Even worse, if you get two of these magnets close together, they can leap at each other with violent force; if a small finger were caught between them, it could get broken.
Description of ActivityCork and Needle Compass
For each compass, put a piece of clay in the center of the bottom of your bowl and put the toothpick in the center so that it stands up. Cut away most of the lid so that only the rim remains.
Cut out a ring of paper, and glue or tape it to the top side of the rim. Dig a hole in the center of one end of the cork that is 1/5 inch deep. Balance the cork on the end of the toothpick.
Fill the bowl with water until the cork floats. The toothpick stops the cork from floating to the side.
Magnetize a sewing needle by stroking a real magnet toward the tip of the needle about 50 times. Make sure to stroke it in only one direction, not back and forth.
Paint the tip of the needle and place it on the cork.
The needle should swing around and point north.
Put the rim in place. Mark "north" on the paper.
Super-Easy Supermagnet Compass
Follow the directions with pictures in Leader Resource 1, Super-Easy Supermagnet Compass.