## Magdeburg Vacuum Plates

April 1, 2013

by: Jon Smith

Teaching the basic concepts of air pressure has always been one of my favorite units in Physical Science.  There are so many great demonstrations, some with long colorful histories.  One classic standby is the use of the famed Magdeburg Hemispheres.  The Magdeburg Hemisphere demonstration was invented in 1656 by Otto von Guericke, then mayor of Magdeburg, Germany.

Having just invented the world’s first vacuum pump, Von Guericke set to work creating a device to demonstrate its valuable contribution to science.  That device was the Magdeburg Hemispheres.  Von Guericke’s original spheres were much larger than those commonly available today and made of thick metal.  He used them to dramatically demonstrate the pressure of the atmosphere by evacuating them and using two teams of 15 horses to attempt and pull them apart.  Of course the horses failed to separate them.

Most spheres commonly sold today are made of cheap black plastic and meant to be evacuated with a typical classroom vacuum pump.  They do a reasonable job of demonstrating the basic concept, but, in my own experience, do not hold up well to normal classroom use.  Over the span of my 20 year career I have probably had to replace these hemispheres at least five times.

When Educational Innovations began selling their Magdeburg Vacuum Plates, I thought that I would give them a try.  I was incredibly impressed!

While the plates lack the traditional hemispheric shape, what is gained from the shape change is significant.

By changing the area exposed to atmospheric pressure to a two dimensional circular surface, my 9th graders had no problem calculating the exact amount of pressure holding the plates together.  In addition, because the plates are two dimensional it allowed the designer to provide three different sized grooves and “O”-rings to actually change this area.  When the area is decreased, the force that holds the plates together is also decreased.  Not only can my students do the calculations to determine the new areas and corresponding forces, but they can “feel” them as well.  Using the largest groove and “O”-ring creates an area that requires roughly 170 lbs of force to separate.  Using the smallest “O”-ring, it only takes little over 60 lbs.

The product also comes with a very nice manual with a suggestion that I had never thought of.  Once I have my students calculate the force required for a given area, I have one student stand on a bathroom scale holding the upper handle of the evacuated plates while another student sits on the floor in front of the first student and pulls downward on the lower handle.  The students then watch the scale and note the maximum weight it records before the plates separate.  This weight, subtracted from the student’s weight, roughly approximates their calculated force.

I particularly like the fact that the vacuum plates come with their own hand pump.  While I own both a classic large laboratory electrical vacuum pump and a smaller “squeeze-type” pump, I love the fact that the included pump has an obvious mechanism that students can see.  The creation of the vacuum between the plates becomes something transparent and understandable rather than a magic “black box.”   This same pumping system is used in Educational Innovations’ mini-bell jars, and I love those, too.

Finally, I am most impressed with the strength and durability of these plates.  My set has been dropped, kicked, and beaten in every way imaginable by 9th graders over the past 5 years, and they still work like they did the day I took them out of the box.  I used to guard my Magdeburg Hemispheres protectively.  Now I pass these plates around the room and just let my students “have at them.”  It’s nice to have the kind of durability that turns a quick “one-off” demo into a truly “hands-on” experience.  Thank you EI!

## Students Dig Archeology and Paleontology

June 26, 2012

by:  Norman Barstow

Simulated Fossil Dig

Archeology is the study of society through the discovery, recovery and analysis of the material culture and environmental data that humans have left behind. The data can include artifacts, architecture, and cultural landscapes. Paleontology is the scientific study of prehistoric life.  It includes the study of fossils to determine organisms’ evolution and interactions with each other and their environments.  Most readers will recognize fictionalized accounts of the action and adventures in the pursuit of archeological or paleontological discovery from such blockbuster films as ‘Indiana Jones’ or ‘Jurassic Park’.  While this exercise may not feature the nonstop action and Hollywood fanfare of those films, it is still a fun and valuable classroom activity, not to mention much less expensive.

Objectives

The student will:

• Practice fossil preparation skills using real tools and techniques by removing real fossils from an artificial matrix.
• Be able to explain the difference between a chunk (broken piece) of fossil and a complete fossil bone.
• Be able to list reasons why broken fossils are more common in nature than complete fossils.

Materials

* Plastic butter tubs (1 per student) OR larger plastic trays (for a student group).

* Sand (use contractor or play sand, clean, with no pebbles)

* Potting soil (to add to matrix mixture and to cover the completed matrix).

* Plaster

* Water (sink)

* Bucket

* Stirring stick

* Small rocks and pebbles (per tub/tray) to add reality to the scene.

* Dental picks (w/erasers on one end, 1 per student) or dental picks with handles **

* Plastic knife

* Toothbrush or other stiff brush. (1 per student)

* Plastic trays (1 per student)

* Ziploc bags (1 per student)

* Permanent markers (1 or more)

* Pith helmet (optional)

**  Available from the Widget Supply Company

Set-up / Preparation

At least 24 hours prior to the class (but not more than 2 to 3 days prior), create one ‘fossil jacket’ per student, or group of students.

1. Set out plastic tubs on a flat surface that can be easily cleaned, such as a counter in your classroom, or outside on the grass, near your sink, water source or hose. Have your rocks and fossils nearby and easily accessible.
1. Combine 2 parts sand and 1 part potting soil to 1 part plaster (a plastic cup is a good part measure) This makes enough in a batch that won’t dry too quickly, but can be used before it dries out too much.
1. Stir dry ingredients together with stick. Add water and stir until consistency is thick but not runny, but also not dry.
1. Spread the sand/plaster mixture into a tub and smooth it out. Place the fossils in the matrix/mixture. Cover with more of the sand/plaster mixture. Repeat for each tub until finished. You will likely have to mix several batches of sand/plaster mixture to finish all tubs.
1. Stick some larger rocks on the top layer and cover with dirt. (optional)
1. Leave to dry in a dry place overnight.

(You may want to experiment with this process well before the class date so that you can judge the consistency you will need to make the sand/plaster mixture and the amount of time and materials necessary for your group. Also, the longer the jackets dry, the harder they become. Plan accordingly for the age of your group.)

Activity

1. Explain to the students that they will be acting as paleontologists, excavating a fossil site and performing the job of a preparator – cleaning fossils for identification.
1. Show students the tools that they will be using. Discuss proper and improper use of tools.
1. The students are now ready to excavate. Pass out a dental pick, toothbrush, plastic knife, and tray to each student, or use a larger tray for a group of students. (It is helpful to have extra hands for this step.)
1. Begin the preparation. The most realistic model of prepping would be to cut the sides of the tub down to the level of the matrix and just work from the top down, exposing more surface area as you go. However, if you don’t want to cut the tubs or work from the tubs, you can have the students carefully remove the entire contents (making sure the matrix remains whole) and then work from the top down.
1. For older students, you can prepare for them or help them prepare a grid, using small nails for posts, and string to mark the areas to be explored.
1. Monitoring progress: remind students about proper technique. Remind students that they are not to ‘stab’ at the fossils. Also, watch to make sure students don’t ‘stab’ their hands as they are holding the jacket, making sure to always point or press the sharp end of the tool away from their hand.
1. Soon, someone will make a discovery. Hand out Ziploc bags (1 per student) and write each student’s name on his/her bag. They can keep their finds in the bag and clean and identify them later. As discoveries occur, talk to students about what they found. Is it a rock? Is it part of an animal or flower? Why do you think that and how can you tell? Make sure that each student will be able to explain to their parents what they have found and how they are different.
1. As faster students finish you can assign them jobs to help clean up or ask them to help others who need assistance.
1. Anyone not finished at the end of the allotted time can take what they have leftover home in their bag.
1. Later, have students identify their cleaned and sorted fossils by comparing them to the Sorting Guide which is included in the Fossil Sorting Kit.

## Dinosaur Mania!

May 6, 2012

by: Michelle Bertke

Both the young and old have a special fascination with dinosaurs.  From the small Nemicolopterus to the larger Sauroposeidon, dinosaurs were magnificent and majestic creatures.  This is a topic students want to learn and adults want to teach.  Luckily, there are many at-home experiments and activities that parents can do to foster their children’s love for dinosaurs.

Impression Fossils

Impression fossils are one way that animals and plants, which are long since gone from this world, leave their mark.  One easy way to show how imprint fossils are formed is with play dough and plastic creatures.  Students can use the play dough (which is easily homemade) as a medium in which to press the plastic creatures.  This will leave an impression with a certain amount of detail.  Have the students compare the fossil imprint with their creature or mix up the imprints and play a matching game.  Use this activity to illustrate what can be determined from an imprint fossil (size or texture) and what cannot be determined (color).

Layers of the Earth

To take the discussion of fossils to a next level, an easy at-home activity is a display of the layers of the earth.  In order to create this you will need a plastic or glass container and different substrates to layer.  These can include sugar, coffee, rocks, dirt, or aquarium rocks.  Start the layering with finer material such as the sugar or coffee.  If you begin with the rocks, the finer dirt will fill in the cracks and the layers will become indistinguishable. As you layer the material put small objects in the layers such as fossils or plastic creatures.  This activity not only illustrates that the earth is made of layers but archeologists can determine where the fossils are located how old the fossils are.  In order help determine age you can add a diagram on one side of your container illustrating this point.

Fossil Dig

Parents can take dinosaur learning even further with at-home fossil digs and fossil sorting.  This is a great activity to help kids appreciate the intricacy and excitement of discovering fossils in their own home.  To make your own fossil dig you will need soil, plaster (that can be found in most craft stores), and fossilsThe consistency of the fossil dig will be based on the ratio of dirt to plaster mix.  The more dirt you have the easier it will be to dig the fossils out.  I recommend basing the mix on the amount of time you have allotted for the activity and the age of the group.  Once the ratio is decided on, mix plaster, dirt, and water together to create a mud with a consistency that allows it to flow without being too runny.  Pour the paste mix into individual disposable container.  Once the containers are filled, push fossils into the mix and set aside to dry.  Once dry, the fossils can be dug out with utensils and tools, from plastic knives to paint brushes.  In addition to digging for the fossils, kids can sort the fossils with supplied fossil sorting sheets in order to better appreciate the role of archeologists.

## The Pollution Spill and the River

May 4, 2012

by: Brian Herrin

### A Working Model of an Environmental Disaster

How to model a chemical spill in a flowing water system using connected siphons

One of the difficulties of modeling a flowing water system is the size of the system and the quickness of the flow.  This often makes demonstrations hard to visualize as things happen so quickly.  The model I designed uses large transparent plastic cups and clear tubing that connects them to easily demonstrate how a river can become contaminated by a toxic spill or dump and how the toxic material slowly works its way downstream creating devastation along the way.  In time, the river will eventually run clean, but the damage takes much longer to disappear, and some damage may be permanent.

Begin by setting up a mock river system using six to ten separate cups.  There is no limit to the number of cups you can use.  The siphon tubes used to connect the cups are made of 6.4mm (inside diameter) clear tubing cut into 40cm lengths.  You can use aquarium tubing and smaller plastic cups but a slower system will result.  You will need one less tube than the number of cups you use.  For a self emptying system, you can insert a smaller tube into the last cup that empties into a larger container.

Each cup in the river should be filled 1/3 with water with water-filled siphon tubes between each cup in the line, as in the diagram above.   To fill a siphon tube, lower one end into a filled pail of water and then slowly lower the other end of the tube into the water allowing the air to escape.  When the tube is completely filled cover the ends with your index fingers, lift the tube out of the pail and place the ends of the tube into two of the side by side partially filled cups above, releasing your fingers when the tubes are under the level of the water in the cups.  If you get a small bubble in the tube, lift one of the cups to allow the bubble to be forced out of the tube by the flow of water from a higher to a lower level.  Repeat until all the cups are connected and the tubes are completely filled with water.  Any large air bubbles may disrupt the flow so be sure to remove the excess air.

Add 2 tbsp (30ml) of an acid base indicator to each of the cups.  This can be made by cutting up a few red cabbage leaves into small pieces and placing them in one cup (250ml) of boiling water.  A much easier way is to use Red Cabbage Extract from Educational Innovations.  The infusion should turn a purplish color.  If it is not dark enough, remove the cabbage pieces and put in another chopped up leaf or two or add a little more extract.  Next, add a pinch (no more) of baking soda (sodium bicarbonate) to each cup.  When the baking soda is placed in the cups of red cabbage solution it should turn the solution in the cups a light blue.  You should now have all the cups filled to the same level with a light blue solution connected by clear, water-filled tubes.  It is essential that all the tubes be filled with water and all the cups are the same color before you introduce your “toxic spill”.

Although the water is not flowing at this time, this is now a model of the river before the “toxic spill”.  Inform your students that each cup represents only one section of the river.  Tell a hypothetical story about railway tank cars carrying a toxic liquid that traveled alongside the river.  Explain that there was a derailment on the way, and the tank cars tipped into the river spilling the liquid.  Mention that the toxic material spilled into the river will ‘kill’ living organisms in the river.  Use the model to explain that if the blue river water receives enough of the toxic material to kill the wildlife in the river, the toxins will turn the water pink.

Now use four or five fast-food vinegar packets to simulate the train cars.  Open them and empty the “toxins” (vinegar) into the first cup.

You should see the water in the first cup immediately change color to pink. Begin adding plain tap water to the first cup.  You will notice that if you pour slowly, the water will gradually siphon into the next cup.  As the water in the first cup (with a higher level of liquid) moves into the next cup, the “toxic waste” will begin to contaminate the second cup.  The result is that the water flowing through the tubes into each subsequent cup will change from blue to pink until eventually, all the cups are pink demonstrating contamination.

By placing a 50cm smaller, water-filled tube made from aquarium tubing into the last cup and draping it over the edge of the table or chalk ledge you can let it pour into a pail so your river will keep flowing as the cups gradually empty.

If you keep adding water to the first cup your model river will gradually run clear. You do not need to have a tube if you empty the last cup now and then without losing the siphon effect.  Emphasize that the model river has cleaned itself but the organisms that have died are gone and until the river repopulates from upstream or downstream where the toxic chemical has been diluted enough, the river will be ‘dead’ along that stretch.This is a very powerful model that is not soon forgotten, and if you accompany the demonstration with the information surrounding a real chemical spill or a toxic seepage into a river, it is a real eye opener on how much damage can result.  Something to remember is that we all live downstream from somewhere else.

## 101 Things Everyone Should Know About Science

November 26, 2011

by:  Dia Michels

Science affects everything—yet so many of us wish we understood it better. Using an accessible question-and- answer format, 101 Things Everyone Should Know About Science expands every reader’s knowledge. Key concepts in biology, chemistry, physics, earth, and general science are explored and demystified by an award-winning science writer and a seasoned educational trainer. Endorsed by science organizations and educators, this book is perfect for kids, grown-ups, and anyone interested in gaining a better understanding of how science impacts everyday life.  101 Things Everyone Should Know About Science, written by Dia Michels and Nathan Levy is offered by Educational Innovations for \$9.95.

Sample Questions!

1.  Name some characteristics of all mammals
2.  Name three of the bodily fluids
3.  What are the three states of water?
4.  What mineral is found in a saline solution?
5.  What do we use calories to measure?
6.  What happens over time when iron is exposed to oxygen?
7.  At the same pressure, which is more dense—hot air or cold air?
8.  How does a semiconductor work?
9.  Each year, Earth revolves once around what?

• the sun
• the moon
• its axis
• the Milky Way

10.  What are the four major directions? In which direction does the needle of a compass point?
11.  The continental divide separates:

• which animals are nocturnal and which are diurnal.
• the Northern Hemisphere from the Southern Hemisphere.
• the direction water travels to the sea.
• where it rains from where it snows.

12.  Why is it colder an hour after sunrise than it is at sunrise itself?
13.  What is a hypothesis?
14.  What is the goal of a double-blind, placebo controlled study?
15.  How can you use a lemon to light a light bulb?

1. All mammals have backbones, are warm-blooded, have hair or fur, and drink their mother’s milk when they are born.

All mammals are vertebrates, which means they have backbones, unlike worms or insects. They are also able to maintain a constant body temperature, which is called being warm-blooded. Mammals have hair or fur at some point in their lives, and the females produce milk for their young through mammary glands. Mammals have large brains with modified skulls, complex teeth, and three ear bones. Their skulls have adapted over time to support their elaborate chewing muscles, and to better contain their large brains. Scientists believe that mammalian ear bones (the malleus, incus, and stapes) evolved from bones that were no longer needed, such as a bone to support gills. There are three orders of mammals: monotremes (egg-layers), marsupials (pouched mammals), and placentals (which account for the majority of mammals, including humans).

2. Blood, sweat, saliva (or spit), tears, breastmilk, semen, urine, mucus, lymph, plasma, serum, and digestive juices.

The human body is composed mostly of water, which our body uses to produce different fluids. These fluids help the body to work properly. Glands are organs in the body that create and release chemical substances through ducts. Glands produce sweat, saliva, tears, and breastmilk. Blood comprises two fluids and it also carries hormones, nutrients, infection-fighting cells, and oxygen. Plasma is the liquid component in the blood, while serum is the protein-rich fluid that remains after blood clots. Lymph is a milky fluid that contains lymphocytes, a type of white blood cell. It plays a critical role in the body’s immune system by filtering out and destroying toxins and germs. In mature males, the reproductive system produces semen, which contains the sperm needed to reproduce. Our kidneys process urine to carry wastes out of the body. Mucus is a thick secretion made by special tissues, including the inside of the nose and throat.

3. Liquid, solid, and gas.

Water exists in three states. We use the liquid state most often in our daily activities, for drinking, washing things, and cooking. Liquids do not hold a shape, but they maintain the same volume. In humans, liquid water makes up about 70 percent of our bodies. Ice, snow, and frost are frozen water. Water’s freezing temperature—the highest temperature at which water will become solid—is 32°F (0°C). Water vapor is water in its gaseous state. Until it reappears as a liquid or solid, it is invisible. Water evaporates into the air from bodies of water and from plant and animal respiration. Water vapor is an important regulator of the earth’s heat. Without it, and other so-called greenhouse gases, our planet would be very hot by day and very cold at night. A gas doesn’t hold its shape or maintain its volume. For example, if you pour one liter of water from a watering can into a bucket, it’s still one liter. If you take one liter of water vapor and release it into a two-liter bottle, it will spread out to fill the entire bottle. At sea level, water vaporizes at 212°F (100°C).

4. Salt.

Minerals (like salt) are natural compounds formed through geological processes. Saline is the term used to describe something, including a solution, that contains salt. The chemical name for salt is sodium chloride. Oceans are huge saline solutions, containing about 3.5 percent salt. Salt is also found in some rivers, lakes, and seas (e.g., the Dead Sea and Great Salt Lake). There are natural salt beds that are thought to have come from the salt water of evaporated ancient seas.

Salt manufacturers obtain salt either from these beds or by evaporating seawater. People have used salt as a seasoning and to preserve food supplies since ancient times. It was even used as money, in the form of salt cakes, by the Hebrews and other societies during Biblical times. There are references in the Christian Bible to salt and its value (e.g., “any man worth his salt.”) In Roman times, salt was an important item of trade and was used as money as well. Roman soldiers received part of their pay in salt, and newborn babies were rubbed with salt to promote good health. To compare a person to the “salt of the earth” is to say that they are valuable and have worth. Before refrigeration, rubbing salt into meat was the only way to preserve it. Salt is an excellent cleaning agent, drives away ants, is an effective antiseptic, and is used in skin treatments. Solutions of salts in water are called electrolytes. Both electrolytes and molten salts conduct electricity. Electrolytes also help the kidneys retain proper fluid levels and help balance the amounts of acids and bases in our bodies. They also help the cells in our bodies maintain a proper “voltage” so that the nerve cells can communicate with each other via electrical signals. Electrolyte drinks containing sodium and potassium salts are used to replenish the body’s water and electrolyte levels after water loss. Excessive water loss, resulting in dehydration, can be caused by exercise, diarrhea, vomiting, starvation, or surgery.

5. Energy.

We use calories to measure heat or energy. Scientists define the small calorie, or gram calorie (c), as the amount of heat it takes to raise the temperature of one gram of water 1°C. The large calorie, or kilocalorie (C), is equal to 1,000 small calories and is used to measure the amount of energy produced by the food we eat. Some items we consume have no calories, like water, coffee, or artificially-sweetened drinks, and provide us with no energy—although coffee and some diet sodas contain caffeine, which can create the illusion of energy. Other foods, such as cake and doughnuts, have lots of calories, but they provide little energy since they are very low in nutrients. These are known as empty calories. Any extra calories we consume beyond what is needed for our daily activities are stored by the body as fat.

6. It rusts.

Rust is the common name for a very common compound, iron oxide. For iron (chemical symbol Fe) to become iron oxide, three things are required: iron, water, and oxygen. Iron oxide, (Fe2O3) is so common because iron readily combines with oxygen (so readily, in fact, that pure iron is only rarely found in nature). Iron or steel rusting is an example of corrosion, an electrochemical process. Water speeds the process because it allows for the formation of hydroxide (OH-) ions. The rust that forms is much weaker than iron; when iron becomes severely rusted, it will crumble away. To prevent rusting (or the oxidation of iron), rustproof paint can be applied—a common occurrence on the Golden Gate Bridge in San Francisco. In other applications, nickel and chromium are added to iron to bind together the atoms and prevent them from rusting.

7. Cold air.

Cold air is more dense than warm air. Air is made up of nitrogen, oxygen, and other molecules that are moving around at incredible speeds, colliding with each other and all other objects. The higher the temperature is, the faster the molecules move. As the air is heated, the molecules speed up and push harder against their surroundings and each other. If the volume of the area is not fixed, this increases the space between the molecules, making the air less dense. For example, when the air in a hot-air balloon is heated, it expands (molecules speed up and spread apart). Now less dense than the surrounding air, the balloon rises. When the heater is turned off, the air in the balloon cools, the molecules slow down and move closer together, and the balloon descends.

8. By conducting electric impulses in a controlled fashion.

Semiconductors have had a monumental impact on our society. You find semiconductors inside most microprocessor chips—the heart of any normal computer. Anything that’s computerized or uses radio waves depends on semiconductors. Semiconductors, often created with silicon, allow the transmission and control of electric impulses in microscopic circuits. The smallness of these circuits has led to portable technology that could not have been built with the previous technology of vacuum tubes. For example, the computing power of a modern laptop computer would have required a large building full of power-hungry equipment and a large maintenance staff were it not for semiconductor technology. A diode is the simplest possible semiconductor device, and is therefore an excellent beginning point if you want to understand how semiconductors work. A diode allows current to flow in one direction but not the other. You may have seen turnstiles at a stadium that let people go through in only one direction. A diode is a one-way turnstile for electrons. Most diodes are made from silicon. You can change the behavior of silicon and turn it into a conductor by mixing a small amount of an impurity into the silicon crystal. A minute amount of an impurity turns a silicon crystal into a viable, but not great, conductor—hence the name “semiconductor.”

9. Earth’s orbit around the sun is called Earth revolution.

This celestial motion takes 365.26 days to complete one cycle. Earth’s orbit around the sun is not circular but elliptical. An elliptical orbit causes the distance from Earth to the sun to vary annually. Because Earth’s axis is tilted in relation to its orbit, the Northern Hemisphere receives longer and more direct exposure to the sun for half the year. For the other half, the Southern Hemisphere receives the warmer weather. The moon revolves around Earth much in the same way that Earth revolves around the sun, but it takes only 28 days for the moon’s revolution. Earth’s axis is the invisible line extending through its center from pole to pole. Earth spins, or rotates, on its axis one rotation every 24 hours, causing day and night. The Milky Way is the galaxy to which our solar system belongs.

10. The four major directions are north, south, east, and west; a compass needle points north.

A compass, often used when hiking or sailing, is a navigational tool used to tell direction. Magnets in the compass align themselves along a magnetic north-south orientation, which causes the needle to align with the magnetic North Pole, so it points north. The compass card inside the glass has the four headings shown as N, E, S, and W (going clockwise) and subheadings of northeast, southeast, southwest, and northwest. Numbers appear every 30 degrees. Long vertical marks occur every 10 degrees, with intervening short marks at 5-degree points. The compass card containing the magnets is mounted on a small pivot point in the center of the card assembly. This allows the compass card to rotate and float freely. The enclosure of the compass is filled with white kerosene to provide a medium to dampen out vibrations and unwanted oscillations. A lubber line is etched onto the glass face of the instrument to enable exact reading of the compass. When a compass points north, it is pointing towards magnetic north, or in the direction of the earth’s magnetic field. True north, also known as geographical north, is the actual northernmost point on the earth, or the center of the North Pole. The two measurements differ because the Earth’s magnetic “north pole” is actually in Canada. In order for an explorer to determine his actual location, he has to know the difference between true north and magnetic north, which changes depending on the longitude.

11. The direction water travels to the sea.

The North American continental divide is a mountain ridge that runs irregularly north and south through the Rocky Mountains and separates eastward-flowing from westward flowing waterways. The waters that flow eastward empty into the Gulf of Mexico by way of the Mississippi and other rivers. The waters that flow westward empty into the Pacific Ocean. Every continent with the exception of Antarctica has a continental divide. Some continents may have more than one.

North America also has an eastern continental divide, which runs along the Appalachian Mountains. Rivers to the west of this divide drain into the Mississippi and other rivers that flow into the Gulf of Mexico. Waterways to the east of the divide flow into the Atlantic Ocean.

Nocturnal and diurnal refers to the active time for an organism. An animal that is active during the day and rests at night is diurnal. An animal that primarily rests during the day and is active at night is nocturnal. The equator, an imaginary line drawn around the earth halfway between the north and south poles, separates the northern and southern hemispheres. Rain is liquid precipitation while snow is solid crystals. There are several factors that affect whether precipitation falls as snow or rain, such as temperature and elevation.

12. Because the planet continues losing heat after sunrise.

We think the minimum temperature should occur at sunrise because the earth has been cooling down all night. The temperature drops throughout the night because of two processes. The earth no longer receives energy from the sun, and the earth radiates energy to space. Overnight, the balance is strongly negative, and the earth loses heat. At sunrise, solar energy again arrives, but the heat loss due to radiation to space dominates until about an hour after sunrise. At that time, incoming solar radiation increases enough to overcome the radiational heat loss.

13. A proposed explanation for why something happens.

In common usage today, a hypothesis (which is Greek for assumption) is a provisional idea whose merit must be evaluated. Science happens in many ways. In some instances, a scientist observes a phenomenon—such as, food left at room temperature spoils more rapidly than food kept cool—and then develops a hypothesis for why. Other times, scientists set out to answer a question—such as, will mice be healthier if they eat vegetables or chocolate. Whether the hypothesis comes from an intellectual pursuit or an observation, the job of scientists is to perform tests in order to validate or negate their ideas. Through rigorous testing, scientists can help us learn what is speculation and what is real.

14. To eliminate the chance of bias.

In a single-blind experiment, the individual subjects do not know whether they are so-called test subjects or members of an experimental control group, but the researchers do. In such an experiment, there is a risk that the subjects are influenced by interaction with the researchers. This is known as the experimenter effect. Double-blind describes an especially stringent way of conducting a scientific experiment. In a double-blind experiment, neither the individuals nor the scientists know who belongs to the control group. Only after all the data is recorded (and in some cases, analyzed) are scientists permitted to learn which individuals are which. Performing an experiment in double-blind fashion is a way to lessen the influence of prejudice and unintentional cues on the results. Strictly speaking, in this type of experiment, every scientist who interacts with or treats a subject should be “blinded.” This doesn’t mean that they are really sight-impaired, it means they don’t know who is receiving a particular test or intervention.

15. Turn the lemon into a battery.

A lemon can be used like a battery by placing a copper penny and a steel paper clip (or a zinc-coated nail) into slits cut into the lemon skin, then connecting the penny and clip with a small piece of wire. The two different metals react with the acid in the lemon juice and cause electrons to travel from the negative terminal (the steel or zinc) to the positive terminal (the penny). An electric potential is created when the different metals are immersed in the lemon, and you can measure this with a voltmeter. One lemon alone will probably not produce enough power to light a bulb, but if you link four or more lemons together in a circuit by connecting the negative terminal of one lemon to the positive terminal of the next, and so on, you may get enough electricity to light an LED bulb, or some other small device.

Dia Michels is the founder and president of Platypus Media, an independent press in Washington, DC, whose goal is to create and distribute materials that promote family life by educating grown-ups about infant development and by  teaching children about the world around them. She is an award-winning science writer who has written or edited over a dozen books for adults and children. She has spoken at national and international conferences for such groups as American Association for the Advancement of Science, national Association of Biology Teachers, La Leche League International, Smithsonian Institution, and the Museum of Science.

Nathan Levy is the author of Stories with Holes, Whose Clues? and Nathan Levy’s 100 intriguing Questions. A gifted educator, Nathan worked directly with children, teachers, and parents in his 35 years as a teacher and principal. He has developed unique teaching strategies that encouraged the love of learning. He has also mentored more than 30 current principals and superintendents, as well as helped to train thousands of teachers and parents in better ways to help children learn.

## Soil Porosity, Permeability and Retention Experiments

August 8, 2011

by: Cynthia House

Demonstration Materials:

• 125 ml graduated cylinder or similar item
• ~100 ml of pea gravel or small marbles
• kitchen sponge
• tap  water

Experiment Materials:

• preforms and racks (three preforms/student or group)
• fine gravel  such as aquarium gravel (~ 30 ml/student or group)
• coarse sand* (~ 30 ml/student or group)
• fine sand* (~ 30 ml/student or group)
• small plastic cups ~ 100 ml capacity
• squares of tulle (“bridal illusion”) and organza, ~ 10 cm x 10 cm
• rubber bands
• electronic balance (capacity at least 100 gm)
• one pound margarine tub or similarly sized plastic cup per balance**
• stopwatch or count-up timer (MyChron Student Timer)
• 125 ml graduated cylinder or similar item
• calculators
• tap water

* Home centers sell sand for sand boxes, landscaping, paving, mortar etc.  Beaches are another source, although you may encounter undesirable contamination. Sifting non-homogeneous sand with a fine kitchen strainer may yield two usable grades of sand.

** secondary containment to prevent accidental spillage of water onto the balance

Background Vocabulary:

Porosity is the measure of how much groundwater a soil can hold, permeability is the measure of how quickly water passes through a soil, while retention is the measure of how much water stays behind.  Even elementary students can relate these concepts to their everyday lives. They observe that some areas in their yards or school grounds form puddles while others drain quickly after a rainstorm. They may wonder why one neighbor’s garden and yard remains lush and green although a sprinkler is rarely used. Children in communities dependent upon well water can understand the importance of replenishing the water table. In most rural and many suburban areas, homes use septic tanks and drain fields to process household wastewater. The “water cycle” is a topic in elementary science curricula. There are many excellent age-appropriate online sources for information on these topics including the United States Geological Survey (USGS) and the GLOBE program.

The commercially available kits I investigated for porosity/permeability/retention experiments were designed for high school students, requiring a level of dexterity not yet developed in many younger students. They also required much larger quantities of test material. One can expect larger samples to provide more accurate results, however, we achieved acceptable accuracy and precision with the method described here.

Procedure:

Set-up: Using the 125 ml graduated cylinder, measure 25 ml of gravel or sand into each preform tube.  Prepare one sample of each material for each student or team of students.  If you have enough material and preforms, prepare some extra samples in the event a group spoils a test and has time to repeat it. The caps that come with the preforms are particularly useful in that filled tubes need not be stored upright for convenient storage or transport. Provide each student or team of students with their samples placed in racks, one piece of tulle and one piece of damp organza fabric, a small cup, several rubber bands, a timer, pencil, and copies of “Procedure” and “Data Table” sheets.

Demonstration:

Model the procedure by following the instructions on the “Procedure” sheet as the students follow along.  Use the 125 ml graduated cylinder in place of a preform tube, and ~100 ml of pea gravel or small marbles. The students will be able to visualize the concepts of “voids” within the sample, and how measuring the water that fills those voids allows one to determine their overall volume.  Although it will move very quickly, point out the movement of the waterfront, and when to start and stop the timer. In particular, point out when to stop adding water, and that adding water very slowly is important with the finer materials so as not to overshoot the mark. I believe that overfilling the tube was the cause of most errors.

Students can easily visualize the concept of retention. Let the students handle a dry kitchen sponge. Soak the sponge in a container of water until it is saturated.  Wring out the sponge, then allow the students to handle the still-damp sponge.

Experiment:

I allowed the students to proceed at their own pace. I work with first through fifth grade students in a science club; for the purposes of this experiment I paired first and second grade students with older children, primarily because of the reading, and the math involved later on. Adults manned the balances both to speed up the weighing process and to reduce spillage. I used two balances for twelve teams of students; if you have more balances available, and somewhat older students, the students could handle the weighing process themselves. They may need to be taught how to tare the balance using an empty cup.

Analysis:

Students fill in the remaining columns in the data table, rounding porosity and retention values to the nearest five percent. They should calculate permeability to two significant figures.  Plot porosity and retention results as histograms, one for each material type.  This experiment lends itself to elementary statistical analysis, i.e. mean, mode, and average. I have included histograms from one of my sessions. The presence of a few errant results, both too high and too low, sparked conversation among the students as to possible sources of error in the experiment.

Clean-up:

The sand and gravel can be rinsed out of the preforms, filtered, then spread out on layers of newspaper to dry for reuse.

Cynthia House is the Science Club Adviser at Olive-Mary Stitt Elementary School

## Our Magnetic Field

June 1, 2010

by:  Martin Sagendorf

We recognize heat & cold, dry & damp, light & dark, and sound & silence.  However… I find it absolutely fascinating to consider that we also live within something that we can’t see, hear, touch, or taste.

We all Know:

Our planet has a giant magnet near its core and that its field extends over the whole of the Earth’s surface.  But, do we ever really think about this field that passes through soil, rocks, buildings… and us? Granted, relatively speaking this ‘field’ isn’t particularly strong.  In fact, it’s a rather weak field when compared to those of a horseshoe magnet or, particularly, a modern Rare Earth magnet.

A Great Demo:

Uses a few very strong Rare Earth magnets to illustrate that this field really is everywhereeven in the classroom.  What we want to make is a really graphic and dynamic demonstration.

It’s Easy to do:

Just hang a magnet from the ceiling – Any bar or ‘donut’ magnet will align itself to the Earth’s magnetic field.  Here’s a very effective construction:

Materials:

• A new pencil with eraser (7-1/2” long)
• 6 rare earth (Neodymium) ring magnets (E.I. Neodymium Ring Magnets #M-185)
• 5 feet of light-weight string or heavy thread (or very light fishing line)
• A ‘flag’ indicating N (cardstock: 3/4” x 2-1/2”)
• A 24” length of 3/4” or 1” wide masking tape
• A few inches of clear tape or Glue (Duco®)
• A very small ball bearing ‘fishing swivel’

Construction:

• Sharpen the pencil
• At 3-1/4” from the top of the eraser, tie one end of the cord around the pencil (look on the Internet to see how to tie an ‘Improved Clinch Knot’ – use two turns – this knot really works quite well)
• Using a single Ring Magnet as a measure, wrap masking tape around the pencil on both sides of where the string is tied to the pencil – wrap-on sufficient lengths to make a snug fit for the magnet (this will be about 12” per side)
• Make up two magnet stacks with three magnets in each
• Use a magnetic compass to determine the ‘polarity’ of the stacks – the stack ends that attract the south-pointing end of the needle are the ‘north ends’ of the magnets – you’ll want these ends to be towards the sharpened end of the pencil
• Slip the stacks of magnets over the ends of the pencil – the stacks will be aligned so they are attractive – carefully move the stacks together (on) each side of the cord
• Hang the assembly from an overhead support
• Place the N flag over the sharpened end of the pencil – centered about 1-1/2” from the pencil point
• The pencil should hang nearly horizontally
• To adjust any deviation from horizontal, add some masking tape on the appropriate side of the pencil
• Once level, use clear tape or glue to fasten the flag
• Splice the fishing swivel into the cord – about 12” above the pencil – use knots as above

In Use:

Suspend the unit from the classroom ceiling such that it is just accessible for ‘spinning’ by students entering the classroom.  This will become an everyday occurrence.

This Simple Device Illustrates:

• That the Earth’s magnetic field is everywhere
• A force we can’t see or feel (directly)
• ‘Force-at-a-Distance’
• That the very small magnetic field (force) from a nearby hand-held magnet is sufficient to cause a disturbance in the ‘local’ magnetic field (even if a magnet is totally grasped within one’s hand – the magnetic field simply goes right through one’s hand)

Notes:

• These little magnets are very strong – be very careful when handling them
• When separating the magnets, slide them apart one-by-one
• When placing magnets together – do so with caution – they will very suddenly attract each other
• These magnets will fracture if subjected to an impact force – wear safety glasses
• Keep the magnets well away from credit cards and other magnetic storage devices
• ‘Spinning’ may result in ‘wind-up’ (a residual twist) in the cord – especially so when using a ‘stiffer’ cord (e.g. light-weight fishing line) – the pencil may ‘come short’ of pointing at North.  The fishing swivel (the smallest one you can find) will minimize this.  But, even with the swivel, there will be times that it cannot completely compensate for the wind-up – if this happens, simply lift the pencil very slightly to release the twist in the cord.  As an aside, fishing swivels usually come several to a package – choose the one with the smoothest action and place a drop of very light oil inside it.

Marty Sagendorf is the author of the book Physics Demonstration Apparatus. This amazing book is available through Educational Innovations and includes ideas and construction details, including all equipment necessary, for the creation and use of a wide spectrum of awe inspiring physics demonstrations and laboratory equipment.  Included are 48 detailed sections describing hands-on apparatus illustrating mechanical, electrical, acoustical, thermal, optical, gravitational, and magnetic topics.  This book also includes sections on tips and hints, materials sources, and reproducible labels.

## Meteorites

May 14, 2010

by:  Ted Beyer

Ever since I was a kid, I have been fascinated with space. I would look up at the stars, and I just knew that other people were up there somewhere, looking back at our little point of light, and thinking the same kind of thoughts. When I was 7 years old, Neil and Buzz landed on the moon, and I was sure that somehow, when I grew up, I would get there, too. (incidentally, that’s me in the red on the right in the picture–and on the left? Well, that’s Buzz Aldrin!)

Dreams can be dashed by reality and time, but the desire can still live on. I became a collector of all things space…and NASA…and then I found that collecting meteorites was not only possible, but also fascinating. Here are objects that spent millions of years wandering through space, only to endure a fiery entry through our atmosphere to end up, astonishingly, in my hands.

The more I researched these space travelers, the more I became fascinated with their vast variety and appearance. When most people think of meteorites, they tend to think of the Nickel – Iron type (or at least I did). Heavy metal, often pockmarked, objects, dull black or grey. Wasn’t I surprised to discover that the Irons make up only about 6% of FOUND meteorites, by number, and 11.3% by weight. In collections, they make up 27.7%. The Chondrites (one form of the stony meteorites) make up 75% by weight and 85% by number found!

In spite of this, my small collection still only has one stony. My one and only stony (so far); pictured to the right, is a slice of the Ghubra meteorite, which was found in Oman in 1954.  See the white spot on the bottom left side of the specimen?  I am assured by experts that the spot, called a chondrule, is older than the planet Earth by as much as 500 million years!

The pride and joy of my collection is one of the rarest types of Irons. A type of Stony – Iron meteorite called a pallasite. Pallasites are made up of Iron – Nickel, but have crystallized almost gem-like grains of olivine, a silicate that varies in color from a brownish yellow to an olive green, embedded in the iron-nickel matrix which can rage up to 1 cm or more in size. These are easily the most beautiful of all meteorite types. As I said, they are also quite rare – making up less than 1% of specimens found. As you might imagine, they fetch a fairly high price (I saved many pennies to get mine).

The first meteorite I acquired was one of the most common and best known. The Campo del Cielo (Field of Heaven) meteorite find is truly vast. Known by natives for uncounted years, it was first found and named by Spanish explorers in 1576 in the Chaco province of northern Argentina. The two largest known masses are 37 and 18 tons and are considered national treasures. Tens of thousands of smaller masses ranging from just few grams to hundreds of kilos have been found, and are often found for sale to collectors.

I have been lucky enough to visit the Tucson Gem and Mineral show several times. This is the largest mineral show on the planet, and is held every year in February. These visits have enabled me to see many meteorites (and even buy a few!), and meet several of world’s leading collectors and dealers. On a recent visit, we were able to acquire some Campo del Cielos that were in somewhat distressed condition (being iron, they were somewhat rusty, having not been properly cared for). I spent a fair amount of time figuring how to stabilize them, and more time to actually do the work and remove most of the rust, so at least for now, they are in pretty good shape. More could be done, but I thought it might be interesting for you to get in on the activity as well.  You can purchase these meteorites that range in size from 160g to 395g from Educational Innovations.

On the same trip, I also found a truly marvelous book on meteorites, somewhat predictably called “Meteorites”. Written by Alain Carion, one of the leading collectors, it is aimed at people who don’t know much about meteorites, but are interested in them, and I read it cover to cover on one leg of my trip home. I learned more in those several hours than I had managed to absorb in the prior few years. I highly recommend it.

I think that people with even a slight interest in space and the unknown will be fascinated by the simple act of holding a meteorite in their hand. An object that has spent the vast majority of its life wandering between the planets – going places that most of us can only dream of going — holds its own magic.

## Ammonite,The Fibonacci Fossil!

November 12, 2009

by: Sara Brandt

Ammonite was once thought to be the petrified remains of snakes! Modern science, however, tells us that these fascinating fossils are actually the remains of an ancient aquatic mollusk.  A mollusk is an invertebrate with a soft, unsegmented body.  The soft body of an ammonite was protected by a hard outer shell. The shells of ammonites ranged from an inch to nine feet! Each shell is divided into many different chambers. The walls of each chamber are called septa. The septa were penetrated by the ammonite’s siphuncle, a tube-like structure that allowed the ammonite to control the air pressure inside its shell. Ammonites were aquatic creatures, and being able to control the air pressure inside their shells meant being able to control their buoyancy.

What is the Fibonacci sequence? The Fibonacci sequence is a list of numbers where every number is the sum of the previous two. The Fibonacci sequence starts at 1 and grows infinitely:

1, 1, 2, 3, 5, 8, 13, 21, 34, 55 …

To put this sequence into mathematical terms, each term Fn = Fn-1 + Fn-2. The Fibonacci sequence can be illustrated geometrically by drawing boxes. The first box should be 1×1, the second box 1×1, the third 2×2, the fourth 3×3, the fifth 5×5, the sixth 8×8, and so on. Each box should be adjacent to the boxes that come before it, forming a spiral of boxes. Have your students create their own Fibonacci squares – graph paper with small boxes works best.

What does ammonite have to do with Fibonacci? Ammonite shells are a naturally occurring example of the Fibonacci sequence. If you draw a quarter circle in each Fibonacci square, they connect to form an ever increasing spiral. Try to find the Fibonacci squares in your ammonite fossils – photocopy the fossil, then start at the very center by drawing two small boxes right next to each other. With most fossils, the first boxes are .25 cm by .25 cm. Continue drawing boxes with Fibonacci dimensions. You’ll notice that the spiral of the shell always falls within the Fibonacci squares.

To further examine the concept of the Fibonacci number sequence in nature it is a worthwhile activity to have your students examine plants and flowers.  So many of them have leaf structures, petals, and stems that follow the series.  These spirals can be seen in everything from sunflowers to pine cones and even pineapples.

If your school doesn’t have access to ammonites, a field trip around the school grounds to identify the Fibonacci sequence in daisies, black-eyed susans, and seed heads would yield many oohs and aahs from your students.  The types of explorations are endless as examples of the Fibonacci sequence and the Golden Ratio are, indeed, endless!

## Real Amber

August 24, 2009

by: Tami O’Connor

What is Amber?
Millions of years ago large forests in some parts of the world began to seep globs of sticky, aromatic resin down the sides of the trees. Unlike sap, resin is produced to protect the tree from disease and injury and is extruded through the bark of the tree during rapid periods of growth.

As it continued to ooze, this resin would trap such things as insects, seeds, leaves and other light debris. As geologic time progressed, these forests were buried under sediment and the resin hardened and formed the soft, warm golden gem we know today as amber. Most of the amber in the world ranges from 30 to 90 million years old and is found in sedimentary clay, shale and sandstones associated with layers of lignite.

Amber is found in the far-corners of the world and is mined from the ground. It can be found from the shores of the Baltic Sea (Poland, Russia, Germany, Denmark, Lithuania), to mountain ranges in the Dominican Republic and Columbia. There is also Romanian, Burmese and Canadian Amber. Amber can be found in the United States and is most abundant in Alaska and New Jersey. This amber dates back to the Cretaceous Period, the age of the Dinosaurs! The size of amber found varies tremendously. The biggest piece of Dominican amber ever found was 18 pounds!

Amber can be hand or machine polished. Professionals use machinery such as sanding wheels to polish amber. They first start with coarser grit levels of sandpaper and as material is removed and they get closer to the surface, they switch to less coarse grit levels to add final touches. Final polishing can be done with a cotton buffing wheel and dental polishing compound. For amber jewelry, holes are drilled with a very fine drill bit. Experts must be aware that amber is sensitive to extreme heat.

Amber actually has the ability to develop a static charge when rubbed with a cloth. In fact, the source of the word electricity is from the Greek name for amber elektron.

The Copal vs. Amber Debate
Copal is a younger form of amber. Much of it from Columbia is said to be up to 10 million years old. Over the past several years, it has become available in great supply. Dealers who sell other types of older and more rare amber, such as Baltic or Dominican, due to their commercial interest, have been trying to convince others to not classify copal as a type of amber. Many scientists disagree, stating that anything made from resin IS technically amber, despite its age.

In the movie Jurassic Park, the storyline was that dinosaur DNA had been retrieved from insect remains found in amber, allowing them to regenerate dinosaur life for the park. Though there are actual insects found embedded inside some amber, this is just a story. Scientists have never been able, in real life, to do this.

Beware! There are actually counterfeit producers of amber who make fake amber using living insects and synthetic resins. Experts have tests to confirm what is real or fake. At Educational Innovations, our amber is real. We only purchase our amber from reputable miners who guarantee authenticity.

Educational Innovations has a terrific hands-on lesson to use with your students as a culminating activity for your geology unit or unit on dinosaurs. This class kit comes complete with everything your students will need to clean and polish actual pieces of amber. Your students will all leave your classroom with a small sample piece as each kit includes 8 one-inch pieces of amber for polishing and 17 smaller amber samples The kit also includes 25 plastic bags to secure samples, 8 polishing brushes, amber polish (aka: gel toothpaste), sandpaper and a complete teacher’s guide. This activity is perfect for the elementary and middle school classroom.

Kit Contents

• 8 large pieces of rough amber to use for class activity
• 17 small pieces of rough amber
• 25 plastic bags for students to secure their amber samples
• 8 polishing brushes
• Tube of amber polish
• 2 Sheets of sandpaper (9×11)