Magnetism stretches out a long way from a magnet, but you can't see it.

To see where it is, you need some very small bits of iron. They can be bought from science suppliers and are called iron filings.

Evenly scatter the filings over a stiff card or sheet of stiff plastic. As shown in the diagram on the main screen.

Then bring a magnet under the card and move it about. The filings will be drawn to the magnet and follow it about wherever it goes.