Educator How-To: The magic of magnetic fields

What better way to understand how magnetic fields work than to see them for yourselves?

Materials:
•    Magnetic field line cards (green) – one per child
•    Magnetic nail polish
•    Clear nail polish
•    Assorted magnets of various shapes and sizes
•    Large clear glass playing pieces
•    Button magnets (at least ½ inch)
•    E-6000 or other silicone glue

Procedure:
1. You will need to purchase some magnetic field viewer cards. They are sturdy and fairly inexpensive, so a single class set will last you a while. (You may also choose to just buy the magnetic film and make your own cards, but it doesn’t have the explanation printed on it.)

Educator How-To: Magnetic Field Magnets

2. Pass out a magnet and a magnetic field viewing card to your students. Try the magnets with the field line cards. What looks the same, what’s different? How do you think the field line cards work? [See the magnetic field viewer cards for more explanation.]

Educator How-To: Magnetic Field Magnets

3. Have the students trade their magnets around and see how the various shapes and sizes of the magnets affect the field viewer.

Educator How-To: Magnetic Field Magnets

4. Give each student a glass piece and place it on the table with the rounded side down.
5. Paint a thin coating of clear polish on the flat surface.

Educator How-To: Magnetic Field Magnets

6. Paint a reasonably thick coating of magnetic nail polish on the flat side of the piece. (Don’t shake your fingernail polish if it has been sitting on a shelf for a while. Instead roll it back and forth in the palm of your hands.)

Educator How-To: Magnetic Field Magnets

7. Quickly (there’s only a small window of time for this) use magnets to create a design now that you know what the magnetic fields will do to the nail polish! You want to put the glass playing piece and the magnets as close as possible without touching one to the other.

Educator How-To: Magnetic Field Magnets

8. Do not pick this up for a few minutes, and allow it to dry.
9. Once dry, use a silicone glue to attach a ceramic button magnet.

Educator How-To: Magnetic Field Magnets

10. Now use your magnets to hang up masterpieces, papers with no name and missing homework!

Educator How-To: Magnetic Field Magnets

How do magnets work?

Questions that often come up are, “How do magnets work?” or “Why is iron magnetic? or “What makes a magnet?” or “What is the magnetic field made of?”

Those are good questions, and they deserve a good answer. However, there is a lot about magnets at the atomic level that isn’t known yet. Just like with most of the other basic forces we are familiar with, such as gravity, electricity, mechanics and heat, scientists start by trying to understand how they work, what they do, whether there are any formulas that can be made to describe (and thus predict) their behavior so we can begin to control them, and so on.

The work always starts by simple observation (that’s the fancy word for playing around with the stuff!) That’s why it’s so important to have some hands-on experience with magnets.

Have your students take two magnets and tried to push like poles together. How far away do you start to feel the repulsion? How does the force vary with the distance between them? When the magnets are moved off-axis to each other (moving them to the side and not head on) what does it feel like? Could you describe it like trying to push two tennis balls together? When you flip one around, what changes? What about moving one around the other in a circle?

Encourage your students to try these things; that’s how you learn! Only when they play with magnets will they begin to understand how they work. This is the stuff great scientific pioneers did, like Faraday, Lenz, Gilbert, Henry and Fleming.

What we can find out through play are some of the basics of magnetism, like:

•    The north pole of the magnet points to the geomagnetic north pole located in Canada above the Arctic Circle.
•    North poles repel north poles
•    South poles repel south poles
•    North poles attract south poles
•    South poles attract north poles
•    The force of attraction or repulsion varies inversely with the distance squared
•    The strength of a magnet varies at different locations on the magnet
•    Magnets are strongest at their poles
•    Magnets strongly attract steel, iron, nickel, cobalt, gadolinium
•    Magnets slightly attract liquid oxygen and other materials
•    Magnets slightly repel water, carbon and boron

Educator How-To: Recycled Plastic Shrinky Dinks

The beginning of the school year is an exciting time for teachers and students alike. We have a quick science activity here that will engage  new students and make your room too cool appropriately cool for school: Shrinky Dinks.

Educator How-To: Recycled Plastic Shrinky Dinks

There are myriad of ways you can use this activity, so the application is up to you, but I am envisioning name plates or name tags, zipper pulls for pencil bags, cubby or tote markers, key chain fobs … the possibilities are endless!

Materials:

No. 6 plastic
Sharpies, colored pencils, or an inkjet printer
Sandpaper
Scissors
Oven or toaster oven
Parchment paper
Non-insulated baking sheet or flat piece of cardboard
Hole punch

Procedure:

The first thing you need to do for this project is to gather is No. 6 plastic, also known as polystyrene. Polystyrene is hard and clear and often used in protective packaging like deli containers. While it can be tricky to recycle, recycled polystyrene can be used in manufacturing rulers, license plate frames, vents, switch boards, and thermal insulation items. Oddly enough, No. 6 plastic can also be whipped into a foam and made into Styrofoam.

For this example, I saved a bunch of lids from aluminum takeout containers, but you can use just about anything that is rated No. 6.  If you want to make an image that will shrink evenly, you will need a piece of plastic that has been stretched evenly. Corners, cups and edges can be unpredictable because they are stretched and molded in multiple directions.

“Plastics are made of long chain-like molecules called polymers. Because polymer chains are so long, they can be manipulated to create a wide-range of properties — in this case for No. 6 plastic, polystyrene. Polystyrene is a thermoplastic, meaning the long polymer chains are heated and stretched, then cooled to form the plastic sheet. The polystyrene remains in this “stretched out” state unless something causes it to change. The cool thing about thermoplastics is that upon reheating the plastic, it reverts to its original state, in other words, it shrinks. This is the same process used to “shrink wrap” items like food containers or other products that have protective plastic wraps.” Lori Steward, Middle School Science

I decided to try something different this time, so I cut the unpredictable edges off my plastic lid in order to get a flat piece of plastic I could trim and run through the printer.

Educator How-To: Recycled Plastic Shrinky Dinks

(If you decide to use sharpies in your project, you can give your students a piece of plastic and a set of sharpies and let them get to work. The sharpie will adhere to the plastic with no problems. If you want to use colored pencils or an ink jet printer, you will need to scuff up your plastic so that there is a bit of texture for the color to stick.)

Educator How-To: Recycled Plastic Shrinky Dinks

I knew I wanted to cut around the outline of my long-horned beetle, but for students you might want a standard shape like rectangles for name tags or zipper pulls. You might also consider using a die cut to make a particular shape — like circles or the school mascot.

If you want to attach a cord or a ring to your shrink dink, you MUST punch a hole in it BEFORE you bake. The standard sized hole punch shrinks considerably.  I always have the urge to use a smaller hole punch, but then I can’t fit anything through the remaining hole.

Educator How-To: Recycled Plastic Shrinky Dinks

Before baking.The larger hole is a standard sized hole punch. The smaller hole is a mini punch.

SO! After I ran the plastic through the printer, I trimmed around my shapes. The “painted lady” was easy as it was a rectangle, but the beetle was trickier.  Since No. 6 plastic is pretty thin and brittle, corners are delicate. You can see in the picture that I had a bit of a problem around the beetle’s tarsal claws. No worries though; the plastic gets tougher as it shrinks.

Educator How-To: Recycled Plastic Shrinky Dinks

Now get out your baking sheet. I like putting a piece of parchment paper down on the baking sheet to protect the surface that you might otherwise put cookies on, but it isn’t totally necessary. If you do decide to use parchment paper, it has a tendency to curl, so you may need to wad up the paper and flatten it back out before using it.

Place your decorated plastic on the cookie sheet and place the sheet in the oven to bake the plastic for 2- 3 minutes on 325 to 350 degrees. Each oven is different, so watch closely!

Danger Note: You are already working with heat, but you might also be working with a possible human carcinogen. No. 6 plastic has been found to leach styrene, so if you choose to do this craft make sure it is in a well-ventilated area!

You will see the plastic curl up and then flatten back out. Wait about 30 seconds longer than you think you need to. Then wait a few more. It is extremely tempting to take the shrink dinks out before they are totally ready, but waiting longer than necessary doesn’t really hurt anything. So resist!

Occasionally your shrinky will decide to stick in a single spot. Not to worry! When you pull the items out of the oven, immediately use something hard and flat, like the bottom of a pie pan, to press out any uneven spots. If you aren’t quite satisfied, you can actually stick your shrunken piece back in the oven and reheat it until it is soft.

Once you remove the piece from the oven, it cools very quickly, so you can handle it almost instantly. I usually pull the cookie sheet out, flip the piece on the kitchen counter and press it flat for a few seconds. By the time I have done all of this, 30 seconds or so, the piece is ready to hold.

How much shrink can a shrink dink shrink? About this much.

Educator How-To: Recycled Plastic Shrinky Dinks

The image on the left is the starting size and the image on the right is the finished size.

Final product!

Educator How-To: Recycled Plastic Shrinky Dinks

Educator How-To: Identifying moon phases

The moon’s appearance in the sky follows a 29.5-day cycle. During the cycle, it first appears as a crescent. The lighted portion that you can in the night sky see becomes larger as days pass, growing until you see a full moon. As more days pass, the lighted portion gets smaller again, until no moon is seen. The cycle then repeats. This 29.5-day cycle corresponds to the time during which the moon makes one complete orbit around Earth.

When you see a full moon, Earth is between the moon and the sun, and all of the lighted half of the moon faces Earth. When there is a “New Moon.” the moon is between Earth and the sun, and all of the lighted half of the moon faces away from Earth. When there is a New Moon, you can’t see any of the moon at all.

Materials:
Paper plates
Copies of moon phases (downloadable here!)
Scissors
Glue
Stapler
Jumbo craft sticks

Educator How-To:

Procedure:
Fold a paper plate in half and carefully cut out the middle of the plate with scissors.
Neatly cut out the moon phases and glue them to the rim of the plate starting with #1 in the 12 o’clock spot and working clockwise.
Staple a jumbo craft stick to the bottom of the plate.
Staple or glue the moon phase key to the handle of the plate.
At night, locate the moon. Holding the moon viewer with the stick pointing toward the ground, frame the moon within the center of the plate.  Observe.  Which picture does the moon most closely resemble? Find that number on the moon phase key and you will know the name for the phase of the Moon you are viewing!

Educator How-To:

Educator How-To: Nautilus and the Golden Spiral (an approximation)

Editor’s note: In honor of our new Nautilus Live program — which takes Museum patrons to the ocean floor with telepresence technology — this month’s Educator How-To is all about the nautilus shell. From our veteran Xplorations educator Kat Havens:

It is difficult to deny the beauty and perfection of the nautilus’ spiraled chambers. Many have heard it is a perfect example of a Golden Spiral or have seen pictures of it neatly fitted into a Golden Rectangle. Although compelling, it is mathematical mythology.

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The angles found within the chambers of the shell exhibit multiple angles that are not congruent with those of the Golden Spiral. In fact, the spiral of the nautilus is more correctly known as an approximate logarithmic spiral or as exhibiting logarithmic spiral growth. Growing in this manner allows the animal to increase in size without changing its shape. We think that it is an excellent example of Mother Nature’s knack for beautiful symmetry.

Materials:

•    Cut nautilus shell
•    Styrofoam or paper plate
•    Sheet of craft foam or other padded surface
•    Paper – color of your choice
•    Acrylic paint – color of your choice

paint print

Procedure:

1.    Gather all of your supplies. Cut nautilus shells are common and may be purchased at seaside shell shops or found online at a reasonable price. They are reusable, provided they are cleaned promptly after each use. We tried cutting our own shells with a fine saw but, we were not completely satisfied with the results.
2.    Place “springy” material, such as craft foam, under the print paper. This allows for a better “pull” as the give in the foam allows for better contact between shell and paper.
3.    Pour a good amount of acrylic paint onto the plate. Manipulate the plate by tipping it around until the paint is spread in an even layer that is large enough to accommodate the shell. Place the shell into the paint and pull it out. You will find the paint may coagulate in the smaller chambers and makes an unclear print. This is solved by gently blowing on these chambers to break the paint bubbles.
4.    Carefully press the shell onto the paper.  Do not move the shell in any direction once contact with the paper is made as it will smear the print. Gently pull the shell up. Often, you can get another decent pull directly after the first print, so feel free to make two or more with one paint application.

nautilus print