Can you solve the MAGNET RIDDLE? ft YouTube CEO Susan Wojcicki

You don't need anything. Just pick one iron block in your palm and through slightly into the air, first with one side up then flip to the other side, and through again. Note whether one side of the selected iron block never flips, and that other slide always flip, then that is your magnet. That is due to the Earth's magnetic field. In our case here in the US, we are closed to the North pole which is in fact the South magnetic pole. So the north pole of the magnet will be attracted to the Earth's South pole, making the magnet either turn or stay still depending on its initial rest position in your palm.