Magnetic Nickels
Three metals are magnetic: iron , nickel and cobalt. Take a nickel from Canada. With clear tape, tape a string to the nickel. Attach the string to the bottom of a stand. Attach a strong magnet to the top. Ring stand work well for this. Raise the nickel to the top and the magnet will attract it.
Canadian nickels contain nickel. so they are attracted to the magnet. Nickels from the USA do not contain nickel. They will not attract. Have students try their nickels. They will not work. Have students figure out why. Eventually they will notice that it is a Canadian nickel.
The USA took nickel out of nickels as the cost to make a nickel with nickel in is more than a nickel