(Reprinted by permission from the introduction to Chemical Demonstrations: A Handbook for Teachers of Chemistry, vol. 4, (Madison: University of Wisconsin Press, 1992))

SCIENCE IS FUN! That is the message that Bassam Shakhashiri personifies as he presents one of his programs on chemical demonstrations. Not only is that the slogan on his familiar T-shirt, but it is also the feeling conveyed by the smile on his face, the enthusiasm in his voice, and the laughter in his eyes. It is obvious that everyone in the audience is having fun, too.

Reading about science is interesting, but seeing it in action is fun.

           Reading about science is interesting, but seeing it in action is fun. And CHEMISTRY is the science that is the most fun of all. It has colour, light, bubbles, fire, explosions, and many other kinds of excitemnet.¹ Chemistry offers a varied menu of interesting topics, most of them relevant to everyday life. It deals with all the matter in the universe, from giant stars to tiny particles inside the atom. It covers foods, fabrics, metals, plastics, plants, animals, and just about everything else. It includes all the chemical elements and their millions of compounds, along with many kinds of interactions, and the instruments and equipment used to study them. Everything we do involves chemistry, from taking a shower or driving a car to just breathing or thinking. Life itself is chemistry in action. Surely there is no subject in the world more fascinating!

Chemical Demonstrations
One of the joys of teaching chemistry is the opportunity to do chemical demonstrations. When I get ready to do a demonstration, the class becomes visibly more attentive. No matter how simple the demonstration might be, students enjoy watching things happen. When chemical principles are illustrated with demonstrations, not only are they more interesting to students, they are also more fun for the instructor.

I suppose it is possible for someone to be a great chemistry teacher without ever doing a demonstration. But why would anyone teaching chemistry want to do that?

           I suppose it is possible for someone to be a great chemistry teacher without ever doing a demonstration. But why would anyone teaching chemistry want to do that? We have such a large repertoire of chemical demonstrations that we could make an appropriate presentation in every single class if we wanted to^2-4. But if we chose to do only two or three demonstrations during the semester, I suspect that those would be the memorable moments of the course for many of our students.
           There are some chemistry teachers who refrain from doing classroom demonstrations because they lack the time for elaborate equipment set-up. It is true that some chemical demonstrations are fairly complicated and time-consuming to prepare. Since most chemistry teachers have to set up their own demonstrations, preparation time is an important factor to consider when deciding whether or not to use a particular demonstration.
           Fortunately, there are many demonstrations that are quite simple to prepare and carry out. It takes very little time and effort to demonstrate the formation of a precipitate, or to add acid to a carbonate to produce bubbles, or to show the colour change of an acid-base indicator. Such demonstrations may sound too simple to be worthwhile, but students are interested in watching them. And when the demonstrations are done at appropriate times during the course, they can add a visual dimension to theoretical discussions, making the topics seem more real. In discussing the effect of surface area on reaction rate, for example, lighting a wooden splint from a candle flame and watching it burn, than tossing a little lycopodium powder into the flame to create a sudden fireball, makes the point much more vividly than can be done with words alone.
           There are hundreds of simple chemical demonstrations that take only minutes to prepare and even less time to carry out in the classroom. Still, they can add a touch of excitement to a chemistry lecture. On the other hand, there is no need to omit the more spectacular but more difficult demonstrations. Most of them can be obtained on film or on video tape or disc, and they can be shown wherever and whenever one wishes to use them.

Overhead Projector Demonstrations
           For the many chemistry teachers who are short on time and resources, there is an especially simple way to do chemical demonstrations. When carried out on the stage of an overhead projector, many demonstrations can be done very quickly and easily. They are usually inexpensive because such small amounts of chemicals are needed, and preparation time and clean-up time are both minimal. But the best thing about overhead projector demonstrations is that students can really see them, even the students way back in the last row. The bright light and large magnification afforded by the overhead projector allow a kind of visibility that cannot be matched on the demonstration desktop, even when a thousand times as much material is used.⁵
           Acid-base colour changes can be shown on the overhead projector using only drops of indicator solution and a few millilitres of acid or base. The shifting of equilibrium can be illustrated with a solution of potassium chromate by adding a few drops of acid and then of base, the colour shifting from yellow to orange and back again. The formation of a coordination compound can be shown by adding ammonia to a solution of copper sulphate, with the initial production of of an opaque precipitate of copper hydroxide and the eventual formation of the deep royal blue tetrammine complex. Chelation can be demonstrated by adding a little dimethylglyoxime reagent to a solution containing nickel ions to produce the cherry-red complex. An entire chemical demonstration can often be carried to class in one hand, or slipped into a pocket.⁶
           Demonstrations requiring the use of devices such as pH meters or voltmeters can be done using an instrument with an oversized dial or lighted digital readout placed on the benchtop, but there are also transparent versions of these meters that can be set up directly on the projector stage. Not all kinds of demonstrations can be done on the overhead projector, of course. Opaque substances all show up as black spots on the screen, regardless of their actual colours, and demonstrations involving fire or explosions are obviously unsuitable for this medium.
           I still recall the very first time I ever saw a chemical demonstration on the overhead projector. It was more than 25 years ago, and the demonstrator was Clark Bricker from the University of Kansas. He added a few drops of ammonia to a solution containing ferric ions. The beauty, simplicity, and clear visibility of that demonstration impressed me so much that I have been doing demonstrations on the overhead projector ever since.

The Tilted Stage
One problem with demonstrations on the overhead projector is that the reactions are viewed from the top looking down, rather than from the side, as we might normally look at a flask or a test-tube. The difference is noticed especially in the case of reactions involving bubbles. With the overhead projector, bubbles often appear on the screen simply as vigorous activity. One misses the fact that bubbles rise in a liquid.
           Hubert Alyea, Princeton's famous professor of chemistry, has been one of the strongest proponents of using projectors to show chemical demonstrations. But he long ago decided that he wanted students to see the bubbles rise when a gas was generated in a chemical reaction. He therefore favoured vertical projection of demonstrations, and for that purpose he designed a special TOPS projector, as well as an adaptor for use with an ordinary projector.⁷ Using the TOPS equipment was a bit cumbersome, but it did provide a more realistic view of many chemical reactions, especially those involving gas generation.
           Then, in 1988 he made a startling discovery. If a thin flat cell is placed on the stage of an overhead projector so that it is inclined at an angle of about 20 degrees, the container appears on the screen to be standing in a vertical position⁸. Objects such as bottles and test-tubes can be viewed as if in a normal standing position, and bubbles can be seen to rise during chemical reactions. A simple tilted support placed on the stage of an ordinary overhead projector, along with some thin, flat reaction 'cells', creates the illusion that the chemical reactions are being carried out in standing vertical containers. The technique is so simple and works so well that one cannot help wondering why it had never been tried before!

History of Chemistry
Another reason why chemistry is such fun to teach is that it has such a rich and exiting history. Although many chemistry teachers feel they must ignore the background material in order to have enough time to discuss all the principles and theories, I think that history is important. More than that, I think it is interesting, and I find that students do, too. The subject of atomic structure is much more impressive when you know something about how scientists were able to figure out what these things called atoms are like.
           There are many fascinating stories about important chemical discoveries; the shiny little globules of potassium metal that appeared when Sir Humphry Davy sent an electric current through molten potash, causing him to dance about the room in a state of ecstatic delight; the 'aniline purple' dye that Sir William Perkin made accidentally when he was trying to make quinine; the whole new family of invisible elements (the noble gases) that resulted from the work of Lord Rayleigh and Sir William Ramsey; the tons of pitchblende from which Marie Curie and her husband painstakingly extracted one-tenth of a gram of the radioactive new element, radium; and the list goes on and on.
           Aaron Ihde of the University of Wisconsin, whose speciality is the history of chemistry, feels the main reason for including history in a chemistry course is to give students an appreciation for the fact that chemistry is a human enterprise⁹. Those famous chemists of past centuries were real people, with human faults and frailties. They made important discoveries, but they could also make mistakes. For example, Wilhelm Ostwald, winner of the Nobel prize in 1909, was possibly the last chemist of his day to accept the atomic theory. In the early years of the twentieth century he was still referring to "those mythical particles called atoms." Relating anecdotes or describing personalities of famous chemists not only catches the interest of students but can help them realise that chemistry is a dynamic field: a theory that is popular today could be replaced a few years from now.
           In learning about famous chemists, one realises what a versatile group they are. The fact that many chemists started out as physicians or pharmacists is not surprising because those fields are related to chemistry. But Joseph Priestley was a Unitarian minister, and John Dalton was a Quaker schoolteacher. Georges Urbain, who did research on the rare earths and discovered the elements lutecium, was a sculptor,a painter, and a musician¹⁰. Many chemists (like other scientists) started out with musical careers in mind. The most famous example of a chemist-musician was Alexander Borodin. Although best known as the composer of the opera Prince Igor and other famous musical scores, Borodin was both a physician and a professor of organic chemistry. Sir William Ramsey, who isolated the noble gases, was also interested in music from an early age; throughout his life he loved to sing and often accompanied himself on the piano.
           A number of chemists have become involved in the law and politics. One of the best examples is Chaim Weizmann, who discovered a method for making acetone and butanol by fermentation; he became the first president of Israel. More recently there was an industrial chemist named Margaret Thatcher who became the first female prime minister of Great Britain.

Humour
Chemistry is a serious subject, but now and then it can have its lighter moments. A cartoon laid on the overhead projector a few minutes before the hour can start a class off with a smile. One of my favourite cartoons is the one by Sidney Harris about the elements. It shows two robed men from ancient times, one of them pointing to a stone wall on which are inscribed the words: AIR, WATER, FIRE and EARTH. The caption is simple: "The Periodic Table."¹¹.
           Once in a while, a joke comes along that is germane to chemistry. For example, there is the one about the chemist who went into a drugstore and asked for a bottle of acetyl ester of salicylic acid. The druggist scratched his head and asked: "Do you mean aspirin?" "That's it" exclaimed the chemist, "I can never think of that name!"
           Most people can tell funny stories based on their own experiences. I recall a Halloween many years ago when one of my sons was in second grade. I had agreed to provide entertainment for his class party at school that day, so I decided to dress up as a witch and do some "magic" chemical demonstrations. I breezed into the room on a broomstick, wearing a long black dress and cape, and a tall black, pointed hat. I also wore a mask so the children would not recognise me. I began pulling bottles out of a big old briefcase I had brought along, saying, "Let's make yellow!" "Let's make blue!" or "Let's make red!" Each time the mixture produced the specific colour. Then I used the 'Old Nassau' mixture¹². When nothing happened, the children yelled: "You forgot to tell it what colour to turn!" So I asked them if they knew what the Halloween colours were. As they started shouting "orange and black," the liquid obeyed by turning orange and then black. By now they were really under my spell! That evening I was taking my four-year-old son 'trick-or-treating,' and we happened to walk past a man with his daughter. After they had passed us, I heard the little girl say: "Daddy! Do you know who that was? That was Ronnie Kolb's mother, and she's a real witch!"

A Final Word
Of course, it might be objected, students enjoy watching chemical demonstrations and listening to stories, but in a chemistry course, students are supposed to learn chemistry. Certainly that is true, but if they happen to find the course interesting and fun, does that mean they will learn less? On the subject of teaching introductory chemistry George Kistiakowsky of Harvard University once said: "It is far more important to be interesting than to be thorough or erudite, for if we have the interest of a beginning student, we can easily lead him to read more on his own or to take further courses that will be rigorous and complete."¹³ I heartily agree. Furthermore, I think a class that is more interesting for for the student is also more fun for the teacher.
           Many chemistry teachers seem to have a genuine love for what they do. Consider Jean Baptiste Dumas, who was born back in 1800. Although he was foremost a chemist, he also held many high government positions, including Senator, Minister of Agriculture, and Master of the French Mint. In his later years Dumas said: "I have seen many phases of life; I have moved in imperial circles, and I have been a minister of state; but if I had to live my life again, I would always remain in my laboratory, for the greatest joy of my life has been to accomplish original scientific work, and, next to that, to lecture to a set of intelligent students."¹⁴
           Having met hundreds of chemistry teachers from all over the United States and from many other parts of the world, I am impressed by the genial enthusiasm that most of them share. Chemistry is hardly a popular subject among students; in fact, they often rate it as "most difficult." After all, much of the time in a chemistry course is spent trying to solve a wide assortment of challenging problems. Teaching chemistry is not easy, but it can be fun!
           I think that Harry Gray of the California Institute of Technology, in accepting the 1991 Priestley Award. spoke for many chemical educators when he said: "It is truly remarkable that I have been able to make a living doing something that is so much fun"¹⁵.

References
1. R. W. Ramette, J. Chem. Educ., 57, 68 (1980)
2. H. N. Alyea and F. B. Dutton eds., Tested demonstrations in Chemistry, 6th. ed., (Easton: Journal of Chemical Education, 1965)
3. B. Z. Shakhashiri, Chemical Demonstrations: A Handbook for Teachers of Chemistry, vols. 1-3, (Madison, University of Wisconsin Press, 1983, 1985, 1989)
4. L. R. Summerlin and J. L. Early, Chemical demonstrations: A Ssourcebook for Teachers, (Washington: American Chemical Society, 1988)
5. E. J. Hartung, The Screen projection of Chemical Experiments, (London: Cambridge University Press, 1953)
6. D. Kolb, J. Chemn. Educ., 64, 348 (1987)
7. H. N. Alyea, TOPS in General Chemistry, 3rd. ed., (Easton: Journal of Chemical Education, 1967)
8. H. N. Alyea, J. Chem. Educ., 66, 765 (1989)
9. A. H. Ihde, J. Chem. Educ., 57. 11 (1980)
10. I Asimov, Biographical Encylopedia of Science and Technology, (Garden City, N.Y.: Doubleday, 1964)
11. S. Harris, What's So Funny about Science?, (Cartoons from American cientist), (Los Altos, Cal.,: W. Kaufmann, 1977)
12. Expt. 10.3 in Bassam Shakhashiri, Chemical Demonstrations, vol. 4, (Madison: University of Wisconsin Press, 1992)
13. G. Kistiakowsky, quoted in E.G. Rochow, Modern Descriptive Chemistry, p.iv, (Philadelphia: Saunders College Publishing Co., 1977)
14. R.E. Oesper, The Human Side of Scientists, (Cincinnati: University of Cincinnati, 1975)
15. H. Gray, Chem.Eng.News., 69(15), 40 (1987)