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L EA TAP C E NT E R PHONE OR 2.5 DOUBLE RN I N TO G ZOOM WITH ACT I VI TY TABLET PENDULUM PICK-UP PhySicS Materials  2 pieces of wood, 16 by 2 by ¾ inches  1 piece of wood, 12 by 2 by ¾ inches  1 piece of wood, 18 by 12 by ½ inches  magnetic wand  string  screw eye  assortment of paper clips, both metal and plastic Center Description A pendulum is a weight that is suspended from a fixed point so that it is free to move. In this STEM center, the weight suspended from the pendulum is a magnetic wand that children can use to pick up various types of paper clips scattered below. Two variables affect whether or not the paper clips are picked up by the magnet: (1) the material the paper clips are made from, and (2) the distance of the paper clips from the magnet. Some of the paper clips are plastic and are therefore not attracted to the magnet; others are made from a metal alloy containing iron and are easily picked up by the magnet; and the third type are covered with a plastic coating but have a metallic core that is attracted to the magnet. Chil- dren will need to investigate the differences between the paper clips that are attracted to the magnet and those that are not. The second factor that affects whether or not the magnetic wand picks up a paper clip is how far away the paper clip is from the magnet. Children may notice that the magnet picks up more paper clips that are directly below it than paper clips that are along the edge of the pendulum frame and therefore far- ther away. As part of the investigative process, teach- ers can help children measure the distance between the magnet and the paper clips when the magnet is at various positions in its swing. Children can mark the 26 c ha P TE R 2 distance on a stick or attach interlocking cubes to use as measurement units. The pendulum frame used in the photograph con- sists of two sides made from pieces of ¾ -inch wood, 16 by 2 inches; a top made from ¾ -inch wood, 12 by 2 inches; and a baseboard made from ½-inch plywood, 18 by 12 inches. The frame is screwed together, as pictured, and the pendulum is suspended from a screw eye. COPYRIGHTED MATERIAL