Bravely ignoring the forecast of a new ice storm, Jack and I are back at work and have great intentions for the new year. One is to compile a comprehensive mailing list of our growing network of professionals interested in improving science education. Another is to broaden the scope of the newsletter to include outside contributions. To this note, the guest scientist for this issue is Dr. Loretta Jones, a chemist. Look for Dr. Jones' comments throughout the issue!

Now back to ice and snow, again. Rebecca Hall's students at Taft Elementary School in Kankakee, Illinois are wondering about snow this month. They ask:

WHY IS SNOW WHITE?

    Things look white because they give off light of many different colors. To many people, the only things that give off light are light bulbs, fire, or the sun and stars, but some things glow in the dark. Snow is not like any of those. Even on the darkest night, when you look outside at snow on the ground it is white. It seems to gather any light there might be in the sky or from a house far away and send the light back so we can see it. This is because snow is made of little pieces which are crystals reflecting all kinds of light, sort of like diamonds do. A big, sparkling diamond can be seen to reflect red, blue, green, and many other colors, but a pile of little tiny diamonds would look very white like snow, because all the colors that each one is reflecting are getting mixed together. So the next question is the right one for this discussion.

WHY IS SNOW MADE OF LITTLE PIECES?

    Snow is made when evaporated water turns into ice instead of turning back into water. That is because it is very cold up in some part of the clouds where snow forms. Evaporated water turning back into water, forms little drops. These drops form on the outside of a cold drink, on cold windows when you breathe on them, and in the air when you breathe out on a cold day. I think that evaporated water is little tiny molecules of water made of one atom of oxygen with two hydrogen atoms attached. One edition of Encyclopedia Brittanica said these H2O molecules only exist in the gaseous state, because when these molecules hook together, they become liquid or solid. What I don't know is if two H2O molecules hook together they have become a liquid or a solid. I don't think so. What I think is that a little speck of dust, a smoke particle, or perhaps a tiny salt crystal somehow attracts the water molecules, and enables many of them to get together into chains or solid blocks.

Snow flakes grow around specks of dust, salt, or smoke, by chains of water molecules sticking onto the speck.

[Dr. Jones adds:

I like Jack's ice-skating analogy, but my mental images are a little different. An ice skater, once attached, can pick up only one more skater, that is, each skater has two hands and can hold on to only two other people. However, if you look at the picture of the chain of water molecules, you can see that each water molecule has two hydrogen atoms which can reach out to other water molecules and an oxygen atom which can attract two more hydrogen atoms in two different water molecules. This means that each water molecule is attached to four others. So I picture the molecular "skater" in a snowflake as having a body consisting of an oxygen atom with the two hydrogen atoms as hands. On the skater's back are two grips, or handholds. The grips skaters then connect, not by holding hands, but by grabbing the grips on the backs of two other skaters. Since each attached molecule picks up three more, the pretty branches of the snowflake begin to form. ]

[Dr. Jones responds: Airborne water molecules spontaneously attach themselves to each other in rings of 6 molecules. Additional molecules then hook up to the original 6 and spread out. There must be some water molecules in the third dimension since the snowflake seems to be thicker than one molecule,

but the addition is generally in the plane of the original 6 molecules. So, when you see your, next snowflake, think of the tiny ring of 6 water molecules at the center.]

Two or more snow flakes can stick together and a lot of snow falling gets into clumps of many round snow flakes.

    [Now Loretta Jones has a question about snow. She asks:
Why is it that, although each snowflake is different, within a single snowflake the six points are the same or nearly the same? Once the crystal structure begins to form, each point seems to grow according to some preset plan. How do the new water molecules attaching themselves to one point know to attach in exactly the same manner as those in the other points? How do they know the plan?] Do any of our readers have an answer for our guest scientist?

    Hal Taylor sent us some beautifully illustrated questions from his first graders at Lincoln School, Ypsilanti, Michigan. Hal asked them what they wanted to learn about science this year. The answers were wide ranging, showing the children's interest in snakes, butterflies, caterpillars, dolphins, eagles, puppies, trees, and the wind. One student wanted to know about sleep and drew a nice picture of herself in bed. I bet she'd be surprised to know that Time  magazine, (December 17, 1990), recently did a full length feature on American's lack of sleep and its deleterious effect on productivity. Time reports that mental fatigue contributes to human errors causing from 60% to 90% of all accidents in the workplace and that "inadequate sleep is a major factor in human error." If a typical adult needs eight hours of sleep to function well, I know a lot of teachers who regularly cheat themselves of a good rest. Balancing lesson planning, grading and juggling family needs leaves little time for sleeping.

Most children would be surprised to know that researchers find adults do not get enough sleep. Kids are constantly being told by their parents to get to bed when they are not tired. Perhaps it is the children who should be sending their parents to bed early!

We enjoyed deciphering Hal's students' invented spelling--one wrote that he wanted to learn about "camisstree". I like that one, and I loved the picture he drew of test tubes with exploding experiments!

HOW DO BEES MAKE WAX?

A1.   One student from Hal Taylor's class asked, "How do bees make wax?" I consulted The Insects, from the Life Nature Library for a preliminary answer, (Time-Life science books have provided many handy answers during my years of classroom teaching.)

    In its larval stage, a young bee spends all of its time eating, averaging 1,300 meals a day! When the bee grows up, it starts to produce wax from glands located under its abdomen. The wax is extruded from between the segments of the abdomen in little chips called scales, which are poked out by the bees hind legs and passed up to its front legs.

(Think of where we humans produce wax!) The bee then chews the wax and molds it into a hollow column like all the cells that make the honeycomb:

The next cell uses one side of the first column, and the next cell uses one side of each until the bees have made a comb, ready to be filled, some with honey and some with eggs.  The top of the honey comb then looks like this. Honey bees use a hexagonal shape for their honeycombs. This shape holds more honey than a triangular or square shape and is also quite strong when reinforced by its neighboring cells. Scientist Charles Darwin, more than a hundred years ago, said that a beers architecture was an example of "the most wonderful of known instincts" and "absolutely perfect in economizing labor and wax." Scientists studying honeycombs at all stages of construction have noticed that bees start and finish their cells in the shape of hexagons. -MO

[Dr. Jones adds: A U of I chemist read that the hexagonal shape holds more honey and pointed out that any shape can be used to hold a given amount of honey. Does the article mean that less wax is needed if the cells are hexagonal rather than square or triangular? Would even less wax be required if the cells were octagonal? Probably not, since octagonal cells cannot be made to fit together without some additional square shapes--(try it! ). ]

Jack discovered some interesting drawings that illustrate how a honeybee makes wax in the book, Animal Biology, by Michael F. Guyer.

WAX MANIPULATION BY A HONEY BEE

---

    These drawings show the location of wax scales underneath the abdomen of a bee. (The white spaces indicate the wax plates.) The bee removes a wax scale from her abdomen with one hind leg while supporting herself on three legs. This side view shows the bee passing the wax scale from her hind leg to her forelegs and mandibles. Finally, the bee chews the wax scale, making it pliable and easy to manipulate into the wax column. DID YOU KNOW...that only female bees make wax and honey?

Q2. HOW DO BATTERIES WORK?

Bobby B., another of Hal's first graders wrote, Hou das Bateirs Wrok?

Jack answers:

The battery that Bobby drew looks like the kind you put in flashlights or toys. It seems very complicated to explain, because such batteries are full of chemicals, and we might need to know a lot about chemicals.

You could make a simpler battery if you had two different kinds of metals like a piece of copper and a piece of zinc. Pennies have enough copper in them to give them their color, and galvanized buckets are steel coated all over with zinc. I'll have to try to see if

I can find the handle of a galvanized steel bucket and a penny to make a battery. You'd also need a chemical that makes electricity on the surface of the two metals, usually an acid or an alkali. Lemon juice has a lot of citric acid in it, but vinegar has acetic acid in it. So one of those might work. Another way would be just to cut two slits in a lemon and stick two different kinds of metal in them.

The next problem is to see if our home made battery is working.

Now, we come to the real question: How does this battery work?

A piece of copper in acid dissolves a tiny bit, and the main parts of copper atoms on the surface move away from the penny, leaving behind two electrons (little pieces of electricity) which run through the penny and down the wire. A piece of zinc in acid loses parts of its atoms into the liquid, too, making electrons run through the handle.

The difference is that lots more zinc atoms dissolve in acid than copper atoms, leaving lots more electrons crowded together in the zinc-coated handle than in the penny. The result is that electrons jump across a tiny space from the zinc handle to the wire, just before they touch, to get more room. As the electrons jump through the air, they make it hot, and a tiny explosion or spark occurs. If you touch the wire and the handle both at once to the tip of your tongue, the electrons would run through your tongue to get to the penny, giving you a little shock.

[Dr. Jones adds:
    A chemist told me about the time he formed a battery inadvertently in his freezer. He stored barbecued chicken coated with a sweet-sour sauce in a steel pan, covered the pan with aluminum foil, then stowed it away in the back of the freezer and forgot about it for several months. When the chicken was retrieved, he found a group of pinholes in the aluminum foil everywhere the chicken had touched. The two metals, iron and aluminum, had formed a battery with the aid of the acidic barbecue sauce. The aluminum atoms lost electrons to the sauce wherever it contacted the sauce. The reaction would be very slow at the low temperatures in the freezer and probably occurred mostly during the defrost cycles.

A similar experience happened to me once while I was cooking food in tomato sauce using a cast iron pot that I covered with aluminum foil. Everywhere the food touched the foil, holes appeared in the foil. The aluminum was being dissolved in the food! I learned from that experience that it is never a good idea to cook food in a metal pot, using a different metal as the lid or even as the stirring spoon, if the spoon is used long. Some metals, like iron, are good for us in small quantities, but aluminum can be harmful. ]

Cynthia Palmer's class at the Kennedy Upper Grade Center in Kankakee, Illinois is involved in studying eggs and embryos. They are perplexed by how the embryo lives contained in an egg. One student asked, "Does a baby chicken within the egg breathe oxygen? If so, doesn't he run out of air, because there is just a little air space?"

Jack answers:

    Chick embryos in the egg get the oxygen they need, and also get rid of their carbon dioxide gas, through tiny holes in the shell. By the fourth day of incubation, the chick embryo is forming a thin membrane full of blood vessels that spreads as it grows all around the inside of the shell. This membrane is called the allantois, and it absorbs oxygen through microscopic shell openings and sends carbon dioxide out through the same tiny holes. By the tenth day of incubation it is full sized, surrounding the embryo, the yolk, and most of the albumen that hasn't been used up by the growing chick embryo. (I got this information from Patten, Embryology of the Chick, Third Edition.)

    This membrane is thinner than the skin between the toes of a frog, but is even more full of blood vessels. It is connected to the chick embryo's belly by a stalk, like a very short version of an umbilical cord in humans or other mammals. However, after the chick is fully developed, it makes a hole in the shell and starts breathing with its lungs. Then the chord and the allantois are not needed any more and they are absorbed by the chick. So, if we let the chick wait until it is ready to come all the way out of the shell, as we should, we never see the chord or the allantois. That is why chickens have no belly buttons. (I got this information from Elsa Carmen, who regularly helps future teachers hatch eggs in our science education center.)

    I have noticed the pores in an egg shell in two ways. By holding a piece of egg shell in front of the lens of a slide projector, with the projector lamp turned on, you can see that a lot of light gets through the shell everywhere. But, in certain places, there are tiny extra bright spots of light you can see with a hand lens suggesting that the hole or holes there is/are larger than usual. The second way is to make bubbles of carbon dioxide come through an egg shell under water where you can see them. I haven't finished working on this experiment yet, but I'll tell you what I have done so far. Perhaps you can think of a better way to do it.

    What I did was to take a fresh egg from the grocery store, and I made a little hole in one end with a large needle, and a larger hole in the other end, just large enough to put a soda straw through. I stirred up the yolk with the needle, and blew in the small hole until everything came out the large hole into a cup. (I put the cup in the refrigerator -- scrambled egg for breakfast.). Then I stopped up the small hole in the egg by dropping candle wax on it. I held a match flame down close over the little drops of wax to melt them again so they would stick to the shell and seal the small hole tightly. Then I put that egg, along with some small pieces of old egg shells my wife was saving for compost in a small glass of water. The large hole was sticking up out of the glass, and with a soda straw I put soda water in the small end of the egg until it was nearly full. (I used ginger ale, but I think any kind of soda with a lot of fizz would do.) .

    Soon streams of bubbles were coming out through the side of the shell in certain spots and bubbling up in the water outside. I believe the bubbles came from the ginger ale inside the egg, because, for a long time, there were many more bubbles forming on the egg than there were bubbles forming on the little pieces of shell in the bottom of the cup.

    I also know that oxygen molecules are smaller than carbon dioxide molecules, so I believe they can get through shells easily too. I haven't thought of a good way to get oxygen to bubble through a shell, but I'm working on it. Fish get their oxygen out of the water they live in. Perhaps if I boil water to get rid of the air in it, and after it cools down, I put that water on the outside of a shell and fresh tap water on the inside of a shell, air bubbles might come through the shell like the carbon dioxide bubbles did. That sounds like a few more hours of experimentation. (Experiments almost never work the first time you try them.)

    Science learning can be at various levels. For example, Predictions, Observations, Explanations, Measurements, are very useful processes to be able to use in new situations. So as children practice those processes in class, we would hope they would become better at them in new situations. We could ask students to think about a new situation and see if they use the POEM procedure Some new science tests are emphasizing such processes.

    Science learning involves molding ideas that could be used in somewhat different situations from the ideas in which they were learned. Thus, by using mirrors in class to reflect sunlight into different spots in the room, predicting, observing, and explaining what people will see in mirrors placed in different places, we might expect children to begin to understand that light often travels in straight lines. Being able to state that idea is pot evidence of useful understanding of that principle. It is useful to be able to recognize other situations where the idea that light is traveling in straight lines explains a mystery..

    For example, in the situation on the top of the next page, a pencil is used to make a round hole in a card, which is placed on a white sheet of paper. Out of the people I've tried it with, teachers, university students, professors, and children, only one, a third grade girl, correctly predicted what the spot of light in the hole would turn into when the card was raised an inch or so. But, having observed the image of the ceiling lights that shows up under the card, and discovered that different colored lights or temporarily blocked lights, show up on the opposite end and opposite side in the image, a number of people of all ages have come up with the idea that light travels in straight lines.

    I would like to assess this learning in a class as a whole, but it might also be done on an individual basis. For example, after doing the experiment, if the various explanations children have given were printed on a ditto sheet and each child or small group of children were asked to circle the ones they feel are the best and cross off the worst explanations, we could compare one class with a previous class where the mirror study was done differently. This is a kind of transfer task, and individual children often do poorly on transfer tasks for unknown reasons. With a wide variety of explanations and plenty of time to think, even to discuss the explanations in small groups (2-4), I think a good comparison could be made between one class and another.

We have some new questions that reached our desk as we were about to go to print. Why don't you venture an answer to the questions below? If we print your answer, you will receive a semester's subscription to the newsletter free. Teachers, why not ask your students to try to answer the questions? We'd appreciate their input as well.

Elizabeth Easley asks two questions:

Why is it, when you mix different kinds of cereal in a cereal box, the kinds with the smaller pieces go to the bottom and the kinds with the larger pieces stay on top, even if you shake them up together?

Why is it that cars with front-wheel drive skid less in the snow and ice, and why were passenger cars only equipped with rear-wheel drive for so many years?

GUEST EDITORS

As I mentioned earlier, we have decided to implement one of Jack's ideas in this issue. The thought is to have a guest scientist or science educator review our newsletter before we send it out. The featured scientist will then add comments reflecting his or her knowledge of the field, therefore making the Science Network

News twice as interesting and valuable! In return for their assistance, contributing professionals will receive a free subscription to the newsletter.

This issue's guest scientist is Loretta L. Jones, a lecturer in the School of Chemical Sciences at the University of Illinois and Associate Director of the General Chemistry Program. Dr. Jones was kind enough to tackle our rough draft over the weekend, and we are delighted with her response!

May R. Berenbaum, Professor of Entomology at the University of Illinois also contributed to this issue. Professor Berenbaum is well known for her annual film festival on insects!

If you would like to be a guest scientist, please let us know. We'd like to have contributions from our readers--especially ideas from teachers working directly with children. Don't worry about format, that's what editors are for- just send your comments, anecdotes and ideas. Every contributor receives a free semester's subscription to the Science Network News. -MO

 Director Jack Easley
 Editor Michele Olsen