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COPYRIGHTED MATERIAL Connections to Technology and Engineering Science Content The pendulum weight is called a bob, and the time that the pendulum takes to swing back and forth one time (for example, left to right, and back to the right again) is called a period. These are terms that children will quickly acquire if teachers model them while children explore the pendulum. A magnet is an object that produces an invisible magnetic field, a force that pulls other ferromagnetic materials (chiefly iron) toward it. It is incorrect to tell children that magnets attract all metallic objects, because in most cases this is true only for materials that contain iron. Notice that magnets will not pick up an aluminum pop-top, a silver necklace, or current American coins, although these objects are made of metal. Kindergarten and older preschool children may be interested in the book What Makes a Magnet? by Franklyn M. Branley. Mathematics Content Two areas of mathematics are involved in the inves- tigations in this STEM center: number concepts and measurement. To integrate number concepts, teach- ers can help children count the number of periods before the pendulum comes to rest. Also, if teachers clap a steady beat along with the children and count the number of claps per period, children will discover that even though the arc of the pendulum gets smaller and smaller, the number of claps per period remains the same. Teachers can also help children measure the distance between the pendulum bob (magnet) and the paper clips, as previously described. During their life experiences, children may have noticed the wrecking ball on a crane that is used to knock down buildings. This is an application of the properties of a pendulum to achieve an engineering- related purpose. The wrecking ball is the bob of the pendulum. Children’s books, such as Bam, Bam, Bam by Eve Merriam and Machines at Work by Byron Barton, document this process. Comments and Questions to Support Inquiry • Why does the pendulum pick up so many more paper clips from the middle of the tray? • Here’s another magnetic wand. See if it will pick up any paper clips from the edge of the tray. Does it? Then why doesn’t the magnetic wand on the pendulum pick up the paper clips on the edge? • Which paper clips don’t get picked up by the magnet? • I agree that the magnet doesn’t attract the plastic paper clips, but this paper clip got picked up, and it looks like plastic. • Can you figure out how close the magnet has to be to this paper clip before it will pick it up? • Let’s count how many claps it takes for the pendu- lum to go back and forth each time. Misconception Alert Adults often tell children that magnets are attracted to objects made of metal. This is inac- curate. Magnets are mainly attracted to objects that contain iron. COPYRIGHTED MATERIAL ST E M lE aR n I ng c E n T E R S 27