An iron bar can be magnetized easily by aligning it with the magnetic field lines of Earth and striking it lightly a few times with a hammer. This works best if the bar is tilted down to match the dip...

An iron bar can be magnetized easily by aligning it with the magnetic field lines of Earth and striking it lightly a few times with a hammer. This works best if the bar is tilted down to match the dip of Earth’s magnetic field. The hammering jostles the magnetic domains in the bar so that they can fall into a better alignment with Earth’s magnetic field. The bar can be demagnetized by striking it when it is oriented in an east-west direction.