Test the strength of a bar magnet by seeing through which materials it can pull a paper-clip. First, place a paper-clip on a thin piece of cardboard, as from an old box. Hold the cardboard with one hand, and place the paper clip on top. Hold the bar magnet beneath the cardboard, directly under the paper clip and see if you can move the paper clip across the board with the magnet. To make things more interesting, place the cardboard on a thin table, and see how much more difficult it is to pull the paper clip. On the third try, place obstacles of different material, such as wood, aluminum and plastic, and attempt to pull the paper clip around the obstacles.
See how water affects a magnet's pull by attempting to rescue a paper clip from a glass. First, fill a glass with water into a paper or plastic cup and place a paper clip inside. Take the magnet and hold it to lowest level of one of the cup's sides. Attempt to pull the paper clip upward through the water. Attempt to pull it out from the cup. Be sure to observe how the magnet affects the water, and attempt to pull the paper clip out from the cup without splashing the outside surface of the cup.
Test the polarity of magnets by placing two needle magnets into a paper bowl. First, needles can be magnetized by tapping them on the eye around 30 times with a bar magnet. Test the needle-magnet on pins, seeing if it pulls them, before using them for this experiment. Once ready, place the needle-magnets on one side of a piece of cardboard and put the piece of cardboard into a bowl of water, making sure that the cardboard is placed horizontally so that it can temporarily float. The cardboard should float before it gets water-logged, and the needles aren't strong enough to sink the cardboard. For one experiment, test the needles with their eyes (magnetized ends) facing each other. Then, turn one of the needles so that its eye faces the same direction as the other needle's eye, and both needles are aligned in a straight line, and not parallel. Observe how the magnets react to each other as they float on the water. This experiment shows polarity of magnets through the forces of attraction and repelling. The water better illustrates the magnetic forces, as holding the needles in your hand makes it difficult to show the movement these forces can create.
To create a compass, first fill a bowl or pan with water. Place a bar magnet on top of a piece of wood, and then place the wood with the bar magnet in the center of the bowl of water. The wood and magnet will rotate and spin like a compass. Once the bar magnet and wood stops rotating, observe the direction the bar magnet is facing (it's rectangular so it will point in a direction). Line up a compass at the side of the wood and bar magnet, and observe which direction the compass points. It should line up with the rectangular bar magnet, with one side facing north and the other south. You've created a compass.