Equipment:
1 battery (1.5 volt AA) - do not use a higher voltage for this experiment
2 lron nails
1 elastic band about the same length as the battery
Small piece of wire wool or fine sandpaper
1 shallow (1" or 3cm) glass dish - a dish lid or a glass ashtray would be ideal

Method:
Clean the two nails thoroughly with wire wool or fine sandpaper. Fill the glass dish with water. For this experiment you should NOT add salt - as it will affect the type of reaction that occurs.
Wrap the elastic band around the nail lengthways, so that it covers the terminals. Gently pull the band away from each terminal, and place a nail under it, allowing the band to hold the nail firmly in place against the terminal. Tie a knot in the band ay the back to make a smaller loop. Your finished apparatus should look like the left hand picture below :

Make absolutely sure that the band is tight enough to hold the nails in place, and that the shaft of each nail is in contact with the battery terminal. Place the tips of the nails into the water in the dish, leaning the battery against the side. Use the knot tied in the elastic band as an anchor on the lip of the dish. The battery should not be in the water, only the tips of the nails. Secure the battery using adhesive tape if necessary to make sure that it does not fall into the water. Your completed experiment should look like the right hand picture above.

Observe the experiment immediately. Can you see any reaction ? Look very closely at both nails for a minute or two. Take notes of what you can see. Observe the mixture after 5 or 6 hours. Has any corrosion occurred ? Which items have corroded? Rate the level of corrosion of each of the items from 0 to 5 (0 being no corrosion, 5 being very corroded). Observe for a final time after 12-15 hours or longer.