Features
Magnets: A first step to high tech
by Barbara Langham
No science or discovery center would be complete without magnets. Activities with these common objects not only delight children but also help build a foundation for future learning about metals, geology, electricity, and electronics.
The invisible nature of the magnetic force as well as the fun of playing with magnets can give the impression that magnetism is magic. But magnetism is science. It has observable physical effects, it’s consistent and predictable, and it gives the same results in repeated testing.
Expecting a 3- or 4-year-old to understand why magnets work is not developmentally appropriate. A preschooler does not have the vocabulary, knowledge, and experience to understand about the Earth’s poles and magnetic fields, for example. (Most teachers don’t either.) But children can manipulate objects, describe what happens, and document results.
As with all science activities, it’s important for teachers to treat magnets as science and provide correct information, drawing from facts.
Background facts for teachers
Magnets: Discovery and manufacture. How were magnets discovered or made? The NASA website provides this answer:
“The ancient Greeks, originally those near the city of Magnesia, and also the early Chinese knew about strange and rare stones (possibly chunks of iron ore struck by lightning) with the power to attract iron. A steel needle stroked with such a ‘lodestone’ became ‘magnetic’ as well, and around 1000 the Chinese found that such a needle, when freely suspended, pointed north-south.
“The magnetic compass soon spread to Europe. Columbus used it when he crossed the Atlantic Ocean, noting not only that the needle deviated slightly from exact north (as indicated by the stars) but also that the deviation changed during the voyage. Around 1600 William Gilbert, physician to Queen Elizabeth I of England, proposed an explanation: the Earth itself was a giant magnet, with its magnetic poles some distance away from its geographic ones (i.e., near the points defining the axis around which the Earth turns).”
The lodestone was used for compasses—and to make more magnets—for centuries. Ship captains often carried an extra lodestone because the artificial magnets—those made by stroking a needle with a lodestone—in their compasses lost power over time.
In the Middle Ages, lodestone was used to treat various illnesses, everything from baldness to cancer. By the 18th century, lodestone was in such demand and so expensive that it was considered a precious stone and used in jewelry (Ricker 2011).
Clearly the world needed a stronger and cheaper magnet. English scientist Gowin Knight recognized the commercial opportunity when he discovered an improved process for magnetizing steel in the 1740s. His magnets were so strong and long-lasting that they were adopted as the standard by the Royal Navy. Because Knight kept the method secret, other scientists felt compelled to uncover his secret, which led to more research (Knight, Encyclopedia Britannica).
Iron and steel (which is smelted from iron ore) as well as nickel and cobalt are magnetic metals. No other pure metals—such as gold, silver, and aluminum—are magnetic. But mixing a magnetic metal with one or more elements to make an alloy can change magnetic properties (Gibson 1995)
In the early 20th century, scientists began investigating materials other than those based on iron and steel for manufacturing magnets. “By the 1930s, researchers had produced the first powerful Alnico (aluminum, nickel, cobalt) alloy permanent magnets. Even more powerful ceramic magnets using rare-earth elements were successfully formulated in the 1970s with further advances in this area in the 1980s” (How Products Are Made, n.d.).
Scientists at the University of California at Berkeley have developed what may be the strongest magnet in the world, with a magnetic field 300,000 times as strong as the Earth’s. This hybrid magnet measures only 3 feet long but weighs several tons (UCSB ScienceLine, n.d.).
Magnetism and electricity
While scientists were investigating magnetic metals in the 1700s, others were studying what would become known as electricity. In 1752, for example, Benjamin Franklin proved in his kite and key experiment during a storm that lightning is a form of electricity. In 1800 Italian physicist Alessandro Volta invented the battery.
In 1820 Danish physicist and chemist Hans Christian Orsted made a startling discovery: An electrical current flowing through a wire would move a compass needle placed beside it, which indicated that an electrical current creates a magnetic field. The finding prompted other scientists to explain and expand the discovery.
Just five years after Orsted’s discovery, British engineer William Sturgeon wrapped a wire around a piece of iron and connected the wire to a battery. When connected, the wire coil became magnetic; when disconnected, it lost its magnetic force. Sturgeon demonstrated that he could adjust the power of the magnetic field by adjusting the electric current. He had invented the electromagnet (Sturgeon, Encyclopedia Britannica).
Sturgeon—and others—soon discovered that sending an electrical current through a wire coil set between opposing (north-south) magnetic poles would make the coil spin around. That is, one magnetic pole would attract the coil, and the opposite pole would repel it in quick succession, causing the coil to rotate. The rotation could then be used to do work, such as turn a fan blade, and the electric motor was born.
Since that time, scientists and engineers have expanded the use of electromagnetic fields to almost every aspect of modern living. Cell phones, computers, VCRs, and other electronic devices all use electromagnets. Power lines rely on electromagnets in transformers to increase or decrease voltage. In construction, cranes that lift and drop heavy loads of iron beams are operated by switching the electricity on and off.
In medicine, physicians use magnetic resonance imaging (MRI) to clarify problems such as tumors, injuries, and disease that cannot be seen as effectively with other imaging methods, such as X-ray. Studies are underway to determine whether electromagnetic fields may also help improve the treatment as well as the diagnosis of illness and injury.
Electromagnetism continues to be a fertile area of research in many scientific fields, including nuclear physics. CERN, a European organization of physicists and engineers, for example, hurls sub-atomic particles against each other inside a 17-mile circular tunnel near Geneva, Switzerland, for clues on how the universe works. The collider’s decelerator, which records the results of particle collisions, uses eight huge superconducting magnets—that is, electromagnets made from coils of wire that conduct larger electric currents than ordinary wire, thus creating intense magnetic fields. For a photo, see http://home.cern/about/engineering/pulling-together-superconducting-electromagnets.
As another example of research, biologists have been looking into the interaction of magnetic fields and living cells. Many believe that animals such as dolphins, turtles, rodents, insects, bats, deer, and birds, among others, use the Earth’s magnetic field to guide their migrations. In 2012 two Baylor College of Medicine scientists identified cells in a pigeon’s brain “that record detailed information on the earth’s magnetic field, a kind of biological compass” (Gorman 2012).
Exciting as these recent developments sound, we need to remember that the people responsible for them had to start somewhere—and that somewhere may have been playing with magnets in childhood.
Here are a few examples of facts you can present to children.
Preschoolers (4-5 years)
 Some magnets are rocks.
Some magnets are made by people.
Magnets have two ends. One end is the pull end. The other end is the push end.
Magnets attract other magnets with the pull end. That means they can pull other magnets closer.
Magnets repel other magnets with the push end. That means they can push other magnets away.
Magnets can attract only things made from some metals.
Younger School-Agers (6-8 years)
Magnetic rocks are called lodestones.
Lodestones were discovered thousands of years ago.
Some magnets are manufactured from metals.
Iron, steel, nickel, and cobalt are magnetic metals.
Magnetic metals can be mixed with other metals to make magnets. This mixture is called an alloy.
Magnets can attract and repel other magnets. They can attract metal, but generally they cannot repel metal.
Some magnets have a strong magnetic attraction, and some have a weak magnetic attraction. Stronger magnets can attract bigger and heavier objects.
The strongest magnet in the world is 3 feet long and weighs three tons.
A scientist discovered that electricity could be used to create a magnetic field. His name was Hans Christian Orsted. He invented the electromagnet.
Cell phones, computers, iPads® and other electronic devices need electromagnets to work.
Preparing for magnet activities
As in all activities involving children, make sure to observe safety precautions:
Small magnets are a choking hazard. Don’t use them with children 3 years old and younger. These include disc magnets less than 1 ¾ inches in diameter as well as block and ball magnets of similar size.
Don’t use magnets around anyone with a heart pacemaker. They can adversely affect the pacemaker’s operation.
Neodymium magnets are 10 times stronger than ordinary magnets. If one slams against another magnet, it’s possible that chips may fly off into someone’s eye.
Tips for using and storing magnets:
Keep magnets at least 4 inches away from electronics devices such as cell phones, CDs and videotapes, and credit and bank cards. A magnet can ruin devices with data storage because the data is usually written to the device’s memory in magnetic form.
Be aware that magnets can lose their power through abuse, such as dropping them or hitting them with a hammer. Extreme heat of 100 degrees or more can demagnetize magnets, but cold does not affect them.
Store magnets in closed containers to avoid attracting metal debris. If several magnets are stored together, place them in attracting positions (north to south).
Gather the magnets you already have for classroom and home use. Ideally you will have the following:
a horseshoe magnet, the universal symbol of magnets, marked with “N” and “S” on either end,
small bar magnets, which have power concentrated at the ends, the site of their poles, and
wand magnets, which typically have north on one side and south on the other, with the magnet encased in a plastic housing.
You probably already have alphabet letters and numbers with magnets glued to the backs in the literacy and math centers. You may also have magnetic puzzles in the manipulatives area, toy train cars that attach with magnets, and magnetic tiles or blocks in the block center. And you undoubtedly have advertising and decorative magnets on your refrigerator.
If you’re building or supplementing a magnet collection, your best source is school supply companies, either in a retail store or online. Toy stores have limited selections, and craft stores often sell adhesive magnetic sheets and strips. Home supply and hardware stores also sell magnets, but these are designed for carpentry and repair applications.
Place the magnets in various learning centers as appropriate. Encourage children to explore magnets in their free time. Observe their interest, and answer questions as they arise. To avoid the idea that magnetism is magic, ask open-ended questions that start with what.
What do you notice?
What are you trying to do?
What do you think will happen?
What have you seen the other children do?
What did you try?
What happened?
What do you think would happen if _____ ?
After children have some experience with magnets, plan activities for small groups, such as those below. With one exception, all the activities are perfect for the science/discovery center.
Which spoons stick?
(3-year-olds and older)
This activity may be a child’s introduction to the idea that invisible forces are at work in the world. We can see the spoon stick to the magnet but not the force that attracts them. Similarly, we can feel the effect of gravity when we jump up and down, but we can’t see the gravitational force that pulls us back to the ground.
Here’s what you need:
wand magnets
stainless steel spoons
plastic and wooden spoons
1 sheet of green construction paper
1 sheet of red construction paper
1. In the discovery center, invite children to use a wand to explore whether it can pick up (pull) a spoon. If the wand picks it up, place it on the green paper. If not, place the spoon on the red paper.
2. Talk with children about what they see happening. Explain that the wand contains a magnet, and that it pulls, or attracts, a metal spoon. Ask: “What’s the difference between the utensils on the green and red sheets of paper?” (Those on the green sheet are metal.)
Variations: Invite children to repeat the activity using other kitchen utensils (spatula, scoop, and ladle), aluminum cans, and metal combs, for example. Or place 2-inch lengths of pipe cleaners in a bowl, and invite children to dip a magnetic wand into the bowl. If the wide end of the wand represented a head, you would have funny hair! Ask: “What makes the pipe cleaners stick to the wand?”
Make a fridge magnet
(3-year-olds and older)
Invite parents to contribute old and unwanted fridge magnets. You can also buy magnetic sheets at a crafts store and cut them to the size desired. This activity makes a great gift for parents and grandparents.
Here’s what you need:
flat fridge magnets, 3 ½ by 2 inches, one for each child
photo of each child, donated by parents or taken with a digital camera
glue
1. Clean each magnet. It may be possible to remove the ad on one side.
2. Invite children to place the photo on the ad side of the magnet and cut or tear the photo to fit.
3. Glue the photo in place and let dry.
4. Before children take the magnets home, have them try sticking the magnet to things in the classroom, such as a tabletop, metal bulletin board frame, faucet, and plastic cup. Ask: “Who will use the magnet?” and “Where will they probably use it?”
Variation: Instead of a photo, use a child’s art work or writing/scribbling.
Go fishing
(4-year-olds and older)
Prepare for this activity by drawing fish shapes, each 3-4 inches long, on thin cardboard. Cut out the shapes, and invite children to color them in the art center. If you like, paint a box with blue, green, and white waves to represent a pond.
Here’s what you need:
10-15 fish shapes cut from thin cardboard
glue or tape
box about 1-foot square, either plain or painted to look like a pond
2 dowels or smooth rods about 30 inches long
2 lengths of cord or string, each about 30 inches long
2 ring magnets, 1 ¼ inch in diameter
10-15 metal paperclips, one for each fish shape
1. Tie a magnet to one end of each piece of string to serve as the hook. Tie or tape the other end of the string to the dowel to represent a fishing pole.
2. Glue or tape a paperclip to each fish shape. Place the fish in the pond, and invite children to go fishing.
3. Talk with children about what happens. The magnet attracts and holds the metal paperclip. This pulling is magnetic force. Ask: “Could you hear the snap when you caught a fish?”
Variations: Glue or tape plastic paperclips to the fish, and invite children to fish again. Or place other metal items, such as bolts, washers, coins, and bits of aluminum foil, in the box to see which are attracted.
Hunt for buried treasure
(4-year-olds and older)
Ordinary U.S. coins are not magnetic because they are made of combinations of copper, zinc, steel, and nickel (but not enough steel and nickel to make them magnetic). Likewise, Canadian coins are made of varying quantities of metals, notably steel. Until recently, they consisted mostly of nickel, which had been an abundant metal in that country.
Here’s what you need:
an assortment of U.S. coins, such as pennies, nickels, dimes, and quarters
coins from other countries, such as Canada and Mexico
clear plastic bowl
sand
bar and horseshoe magnets
poster board
marker
1. Fill the plastic bowl with sand. Bury the coins near the surface in the sand. Ask children to predict which coins the magnets will pick up.
2. On the poster board, draw two vertical lines and label one “Magnetic” and the other “Not Magnetic.” Draw a horizontal line for each type of coin.
3. Invite children to use a magnet to find the buried coins and indicate their magnetism by making a checkmark in the appropriate column on the chart.
4. Ask: “What’s the difference between the coins?” (color, shape, weight) Explain that not all metals are magnetic.
Variation: Repeat the activity using a mix of coins and other small metal items such as washers, nails, bolts, screws, and staples.
Go through walls
(4-year-olds and older)
Children may already be familiar with the use of magnets to post items like photos and art work to a metal surface. Parents may display grocery lists and calendars on the refrigerator, and you may stick notes to a metal frame. This activity provides an opportunity to observe the action of magnetic force through a variety of materials.
Here’s what you need:
bar and fridge magnets
tray made of stainless steel or another magnetic metal
strips or squares of thin materials, such as paper, hard plastic, cloth, and aluminum foil
strips or squares of thicker and heavier materials, such as cardboard, wood, and leather
1. Invite children to stick the magnets directly to the tray. Observe any difference in magnetic force between different magnets.
2. Ask: “Which part of a bar or horseshoe magnet is the strongest?” (the ends)
3. Ask: “What would happen if we put something, like paper or cloth, between the magnet and the tray? Will the magnet still work?” Invite children to test their predictions.
4. Ask: “What would happen if we put a heavier or thicker material like cardboard or wood between the magnet and the tray?” Invite them to try the other materials. “Would a magnet work through skin?” (earring)
5. Encourage children to look around the classroom for examples of magnets working through materials.
Variation: Take a small group of children into the kitchen when it’s not in use. Give each child a paperclip, and open the refrigerator door. Encourage them to move the paperclip around the inside of the door to see whether it sticks anywhere. (The refrigerator has a magnetized strip under the plastic lining around the inside edge, so that the door will shut tight.)
Go through water
(4-year-olds and older)
This activity offers an opportunity to see whether magnets work through a liquid as well as a solid. Caution: Don’t leave the magnet in the water after use; the iron in it can rust.
Here’s what you need:
clear plastic drinking glass or bowl
water
magnetic object such as a key or earring
ring magnet or bar magnet
short length of string
1. Fill the glass with water. Drop an object into the glass. Ask: “Will a magnet work under water?”
2. Tie one end of the string to the ring magnet and lower the magnet into the water. If using a bar magnet, move it along the outside of the glass. What happens?
3. Repeat, noting the depth at which the object is attracted. Ask: “Can distance affect the magnet’s strength?”
Variation: Drop a flat metal washer into a clear plastic measuring cup filled with water. The cup markings can help measure the distance better.
Make a chain
(4-year-olds and older)
In playing with magnets, children probably have observed that passing a magnet over a paperclip seems to make the paperclip jump to the magnet. Here’s an opportunity for children to see whether they can exert more control over the attraction.
Here’s what you need:
wand and bar magnets
metal paperclips
empty shoebox
tape
ruler or tape measure
1. Invite children to hold a wand magnet in one hand and place a paperclip on one side of the magnet. Then challenge them to place a second paperclip at the bottom end of the first, another on the end of the second, and so forth to make a chain. Measure the length of the chain.
2. Turn the shoebox so that the bottom faces up. Tape a bar magnet to hang over one edge. Place a paperclip on the overhanging end of the magnet, and challenge children to make a chain, as in the first step.
3. Ask children to predict how long will the chain be. Measure its length.
4. Ask: “What is happening to each paperclip?” (It’s becoming a magnet too.) “What would happen if we used a stronger magnet?”
Variation: Invite children to decorate a shoebox with markers, crayons, or wrapping paper. Tape a bar magnet to the inside bottom of the box. Turn the box over, and suggest that children build a sculpture by placing paperclips and assorted metal items on the magnet side.
Attract and repel
(4-year-olds and older)
The concept that opposite poles attract and like poles repel is critical for building a foundation for all future learning about magnets and electricity. Allow children plenty of time to play and test the concept with a variety of magnets.
Here’s what you need:
2 horseshoe magnets, with poles marked
1. Point out the N and S on each magnet, and explain that the letters represent the magnet’s north and south poles. Ask: “What will happen if we place one magnet over the other so that poles are opposite (north to south)?” Invite children to test their prediction.
2. Ask: “What will happen if we turn one magnet around and place N to N and S to S?” Invite children to test their prediction. Observe that like poles push away, or repel, each other. Ask: “Can you feel the magnetic force?”
Variation: Invite children to repeat the activity using other magnets. Hold a wand magnet over a ring magnet, for example, to see how one side of the wand is pulled toward the ring magnet and the other side is pushed away, seeming to float above it.
Make your own magnet
(5-year-olds and older)
School-agers will find it fun to make a simple temporary, or artificial, magnet. This activity uses a nail and bar magnet, but you can use any small piece of metal (paperclip) and any magnet, even a fridge magnet. You can also magnetize the tip of a tool, such as a screwdriver, to avoid dropping tiny screws.
Here’s what you need:
common nail, 2 inches long
bar magnet
paperclip
poster board or paper
1. Invite children to hold the nail firmly on a table top. With the other hand, stroke the magnet in one direction (not back and forth) over one end of the nail. Stroke the nail 20-30 times.
2. Test the nail’s magnetism by touching the stroked end to a paperclip.
3. Encourage children to test the nail’s magnetism again over a few days and chart the results. It will lose power over time.
Make a simple compass
(5-year-olds and older)
Start this activity with a discussion of geographical, or cardinal, directions (north, east, south, and west). Ask parents to help their children observe where the sun rises and sets over several days. When you’re ready to do the activity, try doing it outdoors.
Here’s what you need:
poster board cut into 4 pieces
marker
compass
magnetized nail from the activity above
sink or basin
water
small piece of Styrofoam or cork, about 1 inch in diameter
tape
1. Standing outdoors or by a large window, ask children to stand facing the direction where the sun rises in the morning (east). Mark a large E on a piece of poster board and display it on the playground or in the classroom.
2. Have children turn 90 degrees left (north), 90 degrees right (south), and opposite of east (west). Make signs for each direction and display.
3. Introduce the real compass. Compare the north-south direction of the needle at rest to the signs you have displayed. Explain that this device helps hikers and travelers find their way.
4. Allow children time to get acquainted with the compass. Explain that they will make a compass using the magnetized nail from the previous activity. (If the nail has lost power, restrike it.)
5. Tape the magnetized nail to the cork or Styrofoam, and float it in a basin of water. Observe what happens as the nail comes to rest.
6. Ask children to compare the nail’s position to the real compass and the direction signs in the yard or room. Make sure there are no magnetic objects nearby. Children may wish to mark the directions on the basin.
Variation: Tie a string around a bar magnet and hang the string over the back of a chair. Will the magnet point north-south?
Books for school-agers
Blevins, Wiley. 2004. Magnets. Minneapolis: Compass Point Books.
Branley, Franklyn M. 1996. What Makes a Magnet? New York: HarperCollins.
Fowler, Allan. 1995. What Magnets Can Do, Chicago: Children’s Press.
Gibson, Gary. 1995. Playing with Magnets with Easy-to-Make Scientific Projects. London: NW Books.
Vogel, Julia. 2015. Discover Magnets. Mankato, Minn.: The Child’s World.
References
About CERN, http://home.cern/about.
Famous scientists: The art of genius. 2016. www.famousscientists.org/.
Gorman, James. April 26, 2012. Study Sheds Light on How Birds Navigate by Magnetic Field, The New York Times, www.nytimes.com/2012/04/27/science/study-sheds-light-on-how-pigeons-navigate-by-magnetic-field.html?_r=1.
Gowin Knight, English Scientist. Encyclopedia Britannica, www.britannica.com/biography/Gowin-Knight.
Magnet, How Products Are Made, Vol. 2, n.d. www.madehow.com/Volume-2/Magnet.html.
Magnet safety. n.d. first4magnets®, www.first4magnets.com/tech-centre-i61/health-and-safety-information-i73.
Magnetic Resonance Imaging (MRI), Sept. 9, 2014. WebMD, www.webmd.com/a-to-z-guides/magnetic-resonance-imaging-mri.
Magnetism, NASA, www-spof.gsfc.nasa.gov/Education/Imagnet.html.
Ricker, H.H. III, Dec. 5, 2011. Magnetism in the Eighteenth Century, The General Science Journal, www.gsjournal.net/.
Shell, Barry. Feb.14, 1988. Earth Sciences and Ecology Question #337 (Are Canadian dimes made out of zinc?), www.science.ca/askascientist/viewquestion.php?qID=337.
Theoretical and Computational Biophysics Group. Magnetic Sense of Animals, University of Illinois at Urbana-Champaign, www.ks.uiuc.edu/Research/magsense/ms.html.
Thomas, G.P. Dec. 12, 2003. What metals and materials are used in US coins and banknotes? AZO Materials, www.azom.com/article.aspx?ArticleID=8088.
UCSB ScienceLine, n.d., How big is the biggest and strongest magnet in the world? University of California at Santa Barbara, http://scienceline.ucsb.edu/getkey.php?key=43.
William Sturgeon, British electrical engineer. Encyclopedia Britannica, www.britannica.com/biography/William-Sturgeon. |
