edited by PATR~C~A J. SMITH United States Air Academy High School United States Air Academy, CO 80840
A Unique Demonstration Show for the Elementary lassroom Edward L. Waterman and Larry M. Bilsing Rocky Mountain High School, 1300 West Swallow Road, Fort Collins, CO 80526
Utilizing a unique program of short term professional leaves, we have developed and presented a series of chemical demonstration shows-for elementary school children. The major goal of the one-hour program was to kindle interest and
than forty schools over the past four years performing and discussing a variety of demonstrations for nearly 4,000 children. Criteria for choosing demonstrations require that they be relativelv safe, easilv wortahle,. hiehlv " " visible. and sufficiently illushtive and &forcing of the major concepts we Dresent. Most of the demonstrations we emolov . . are modifications of well-known chemistry taken from standard sources (1-3).l Numerous programs involving participation by both high school and college educators in elementary school science have recently been described (4-9). While these are novel ideas which have far reaching. potential to excite children about . chtmistry. the hi:h .;ht %,I rwt hrr t,ncwlircrs 3 11umht.r and Ioyi5timl n,n&eratim~ ;ISSW i : ~ a~ l tdh ini~~lcn~entinz carrying a chemical demonstration program to elementary classrooms. Foremost among these problems are the safety hazards posed when demonstrations are performed in crowded classrooms that are not eauiooed for handline chemicals nrooerlv. Safety considerations inder these conchions eliminate the use of classical demonstrations which nroduce fire or emit noxious fumes. Our program employs a large number of elegant illustrations of chemistry which we found to have high motivational value for younger audiences and perhaps are even better suited to teaching chemical principles than the more ostentatious pyrotechnics. A second consideration when dealing with young children is that of maximizing learning outcomes. ~ k s i d e iexciting children we think it is important to teach them. We find that with a one-hour lesson only one or two major ideas can be treated successfully and have designed our program accordingly. Finally, a typical high school teacher, burdened with extracurricular supervisory responsibilities in addition to a heavy teaching load, is simply too busy to carry a chemistry show to the elementary schools. This problem was solved a few years ago when our teacher's association and district adminPresented at the State Convention of the Colorado Association of Science Teachers. Fort Collins, CO. February 21, 1981. Many of the demonstrations we employ have commonly been presented as magic ( I , 2).We believe that science demonstrations and the principles which underlie them are sufficientlyinteresting,exciting, thought provoking, and amusing to stand on their own as illustrations of scientific principles and physical phenomena.
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istration implemented a program of short term professional leaves for certified staff. The goal of these so-called "minisabbaticals" was to provide teachers with more freedom to take advantage of professional development activities not normally possible under the traditional system of limited professional leaves. Typical "mini-sabbaticals" range from three to 10 days in length and teachers have used them to attend professional conferences. take colleee short courses not available during the summer, engage in research, write grant proposals, and develop programs for the gifted and talented. Time to develop and carry out the demonstration program described here as well as to write this paper was provided by these unique short term professional ieaves. The Demonstration Show The first segment of the program illustrates a variety of chemical reactions which show that a chemical chanee is associated with a change in color, form, or energy. The concept of density is also illustrated. In the final segment of the program the students are presented with some unusual chemical and uhvsicd ohenomena and. armed with their new awareness of cke&& they decide (kith a little prodding) what is happening. For example, the unusual phenomenon of "educated moth balls" can be explained in terms of relative densities. Students correctly guess that the color change apparent in the "blue flask" is a reaction between the liquid and gas inside the flask. Putting the ideas of densities and gases together they postulate that a heavy gas reacts with the liquid inWgrapejuice to water." After viewing the various clock react&, the students can correctly predict what will happen under a riven set of conditions. The program was tested at grade levels one through six and the size of the audience varied from 25 to 150 students. We found the program to he most effective for grades four through six and concluded that a group of 75 students is an ideal size. Reaction hv both students and teachers was hiehlv - .favorable. and this prbgram has become an annual event in our district's elementarv schools. The maior concewts we wresented and experimerkal details of the*demonscrationsAweemployed follow. Experimental A Color Change Indicates a Chemical Reaction
Inuisible Ink. Using a 1 in. paint brush apply a 1%solution of phenolphthalein in ethanol to a large sheet of butcher paper and allow to dry. Spray with 3 M NHaOH from an atomizing bottle to produce a bright pink message. Patriotic Colors (2.22). Half fill three laree beakers with water. 0.1 M lead(II)nitrate, and 0.1 M copper(~~)niErate, respectively. Add 5
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Number 5 May 1983
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drops of 1% phenolphthalein to the beaker containing water. Spray each in rapid succession with a squirt of 3 M NHaOH. Blue Flask (3,187).Dissolve 5 g NaOH, 3 g glucose and 5 drops 1% methylene blue in 250 ml water in a 500-ml flask. Stopper and shake. The blue color will disappear upon standmg and reappear with another shake.
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A Chanoe in Form lndicates a Chemical Reaction
Precipitate. Mix equal quantities of 0.1 M lead (11)nitrate and 0.1 M potassium iodide solutions. NylonRope (10). Add 4 drops of sebacyl chloride to 10mlof carbon tetrachloride. Stir vigorously to mix thoroughly. Carefully pour onto this organic layer 50 ml of a stock solution containing 0.38 M 1 , 6 ~ hexanediamine (2.2 ml per 50 ml) and 0.76M sodium carbonate (6.0 g per 50 ml). Using a forceps slowly draw from the interface a long strand of synthetic nylon. Dry uersus Wet Reaction. Mix 10 g of dry sodium carbonate with 10 g of dry citric acid. Add 60 ml water containing 10 drops of a 1% aqueous solution of albumin. Repeat using a one-quart zipper-locking plastic sandwich bag as a reaction vessel (omit the albumin) to capture the evolving gas. An Energy Change lndicates a Chemical Reaction2
Dust Erplosion ( I ) . Cut a small hole in the bottom of a one-gallon paint can and insert aplastic funnel. Attach the funnel to one end of a 3 m length af rubber tubing and a large pipet bulb to the other. Place 2 g of lycopodium powder in the funnel, set a burning candle in the can and press the lid on firmly. Stand back and squeeze the bulb. Caution! Use a hlast shield and perform this demonstration out of doors well away from children! The Density of a Material i s Associated with How Heavy It Is
Bricks. Wrap a brick and an equal size block of wood in duct tape Because of the hazards involved in performing highly exothermic reactions in the presence of large numbers of students in closed areas, discussion of a burning candle usually suffices to illustrate energy changes in chemical systems. The dust explosion is performed only when it is feasible to go outside.
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Journal of Chemical Education
and allow the students to compare their weights. After the bricks have been passed around retrieve them and throw a facsimile expanded polystyrene "brick" into the crowd. Immiscible Liquids. Add, in order, carbon tetrachloride, colored water, and hexane t o a tall cylinder. Stopper tightly andseal with tape. Fill a screw-cap culture tube with carbon tetrachloride and water. Invert and shake ta illustrate the behavior of the liquids. Knowledge of Chemistry Can Be Used to Explain Observations
the solution by adding salt or water. Grape Juice to Water (1,124). Add 3 drops of 18 M H B 0 4 (CAUTION!) t o 2 g of dry sodium sulfite in a 500-ml Erlenmeyer. Pour the result in^ sulfur dioxide into 200 rnl of 0.1% aaueous ootassium permanganate containing 1ml of 3 M H2S04.Swirl t o mix. Various Clock Reactions. Prepare and carry out as described by Moss (11).
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Acknowledgment W e would like t o t h a n k t h e m a n s elementary teachers who invited u s i n t o their classrooms and P o u d r e School District R-l for providing u s with leave t i m e t o develop a n d carry o u t t h i s program. Literature Cited (1) Ford,Leonard E., "ChemiealMagic."T. S. DenisonandCumpany. Inc., Minneapolis, 1959. (21 Chen, Philip, "Entertaining and Educational Chemical Demonstrations: Chemiesl Elements Publishing Cu.. Camarillu, CA, 1974. (31 Alyea, Hubert N., and Dutton, Frederic B., '"TestedDemonstrations in Chemistry: Division of Chemical Education, Easton. PA, 1965. (4) Powell, David L., Bromund, R. H., H a p e a , L. W., McElvany, K. D., and Pederso", J. D.,J. CHEM.E ~ ~ ~ . , 5 2 , 7 3 1 ( 1 9 7 5 ) . (5) Haynes. LeRoy W., and Powell, David L.. J. CHEM EDUC.,53,724 (1976). (6) Borer, LondaL., J. CHEM.EDUC.Sd.703 (1977). (7) Cohen,Sheldon H . , J CHEM.EDUC.,56,736 (1979). (8) Hanson. Richard H.,J. CHEM. EDUC.,58,577 (1976). (9) Bergmeiei, Brian D.. and Saundors, Susan R., J. CHEM.EDUC., 59,529 (1982). (10) Bieber, Theodore I., J. CHEMEDUC., 56,409 (1979). (11) Mass, Arthur, J. C ~ ME ~. u c . 5 5 . 2 4 4(1918).
