Electromagnet

Materials:

Copper wire
1 long nail
Battery pack
Aligator Clips

Wrap the wire around the nail tightly leaving sections at the beginning and at the end to connect it to the batteries.
Make a loop at the end of the wire, and sand the plastic coating off so the copper will conduct electricity.
Connect the alligator clips to the loops and to the battery pack.
Turn the battery pack on (if it has a switch).
Pick small metal object with your electromagnet!
The more batteries in the pack, the stronger the magnet will be.