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Chemistry is an elegant and orderly explanation of ourphysical world, sustaining vital advances in medicine, engi-neering, and industry. But lofty modern status belies the slow,painstaking, trial-and-error groping through which chemis-try has evolved over hundreds of years. Early chemistsbrooded over their work, making great discoveries by acci-dent or by startling exception to many previous failures. Thuschemistry is also, and perhaps more accurately, a reflectionof man’s struggle to explain his world and to survive in it.

It seems natural that the teaching of chemistry to newgenerations of students should recognize and, to some extent,nurture this problem-solving heritage. But unfortunately, theadventure of chemistry is often reduced to passive lecturesand cookbook labs that stifle student questions, exploration,and interest. Students conclude that the old masters wereboorish social outcasts and that modern chemistry is the do-main of a nerdy and bookish group they do not wish to join.

The challenge for today’s new generation of chemistryteachers is to create intriguing moments of perplexity thatchallenge students to seek solutions through actually doingchemistry. This is the essence of great chemistry teaching,and is the mandate embedded in emerging accreditation andprofessional certification standards (1). Given the limited re-sources of many classrooms, this is a significant challenge.However, educators can generate and renew vital interest inchemistry through the use of well planned and effectivelypresented classroom demonstrations that attract and engagethe active and visual learners in today’s classrooms.

Reasons for Not Doing Demonstrations

A variety of reasons combine to discourage the regularuse of demonstrations in chemistry classes. Educators, alreadyhard-pressed for time and energy, understandably balk at thetime and preparation required to include demonstrations intheir teaching. Further, many new teachers, including an in-creasing number from nontraditional certification programs,have not been extensively exposed to the value and pedagogyof demonstrations and are uncomfortable with the thought

of conducting them in class. Reflecting this lack of exposureto the use of demonstrations, many of these teachers assumethat doing demonstrations requires the accumulation of ex-pensive materials or kits, thus draining scarce classroom re-sources from other pressing teaching demands.

Unfortunately, quantitative education research does littleto promote the use of demonstrations. University of Michi-gan researchers found an increase in post-clinical understand-ing of chemistry concepts among educators after involvementin an intensive chemistry demonstration workshop (2). Otherresearchers report an increase in student understanding ofacid–base equilibrium after students were involved in dem-onstrations using student movement to demonstrate the ki-netic principles involved (3). This meager research base,though suggesting significant research opportunity, does littleto justify a significant commitment of teacher time and re-sources to the use of demonstrations.

Reasons for Doing Demonstrations

Busy educators should consider how demonstrations canqualitatively address basic classroom concerns and strike tothe very heart of teaching effectiveness. Demonstrations arevaluable because they engage students with chemistry itself,an increasingly rare opportunity for typical secondary-schoolstudents. At home, current commercially-available chemis-try sets are both more costly and more limited in contentsand potential than their predecessors (4). And at school, manychemistry classrooms are poorly equipped and severely limitthe laboratory experiences that teachers can provide. Further,many traditional school laboratory activities are effectivelyprohibited by new safety regulations placed upon reagents,or because of the prohibitive cost of proper waste disposal.Demonstrations help to offset these limitations, allowingteachers to provide some experiences impossible in an openlab or home setting, while requiring minimal equipment andreagents and producing minimal waste.

Modern chemistry textbooks are filled with impressivegraphics and displays of useful data. However, texts still fail

Using Demonstrations To Promote StudentComprehension in Chemistrysubmitted by: Letta Sue Meyer

Milpitas High School, Milpitas, CA 9503

Stan Schmidt*Department of Teacher Education, Brigham Young University, Provo, UT 84602; Stan_schmidt@byu.edu

Fred NozawaTimpview High School, Provo, UT 84604

Douglass PaneeOak Canyon Junior High School, Science Demonstration Team, Lindon, UT 84042

checked by: Melissa KislerDepartment of Chemistry, Kutztown University, Kutztown, PA 19530

edited byEd Vitz

Kutztown UniversityKutztown, PA 19530

Tested Demonstrations

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to develop compelling links between chemistry concepts andreal world applications familiar to students (5). Lack of in-teraction is a serious problem throughout science education:textbooks alone are not helping students to ask questions ordevelop a personalized understanding of concepts (6). Simple,interesting, teacher-directed demonstrations create cogentmental links between previous and new student learning. Andteachers can easily adjust the emphasis of the demonstrationsto maximize this linking, thus increasing the personal rel-evancy of new learning. In such a learning environment, text-books can then be used as a topic-specific reference orremediation tool (6).

Demonstrations can help teachers make the most of valu-able class time. A demonstration conducted at the beginningof class draws student attention almost immediately to thesubject at hand. Skilled teachers can control and direct dem-onstrations to engage students in wondering what is happen-ing or what is about to happen. An unexpected result at thebeginning of class creates a moment of perplexity and a ques-tion: the starting point for a student-initiated inquiry andlearning opportunity (7). Demonstrations provide teacherswith flexibility in fashioning experiences to address the vari-ety of different student learning styles found in today’s class-rooms (8). Students who typically struggle in formalclassrooms (they typically learn visually or through active in-volvement) are the first to be drawn into and benefit fromparticipation in a demonstration activity (9).

At the same time, demonstrations assist in creating apositive classroom feeling and a sense of “community”. Sharedexperiences of interest energize a classroom, breathing life intoclass work, tapping student emotions and creativity, and evok-ing a sense of shared mystery (10). Teacher and students drawcloser together as learners, and discussion based upon per-sonal interpretation of shared experiences is more likely tolead to positive and productive ends.

Modeling is reemerging in education circles as an essen-tial teaching strategy in today’s classrooms (11). Students havebeen programmed by society to expect immediate responsesfrom themselves and others. Demonstrations create oppor-tunities for teachers to model cognitive strategies. A teacherthinking aloud invites students to observe how he or she dealswith perplexity. The teacher can demonstrate the process offraming and nurturing questions that lead progressively toexplanations and underlying concepts. For students, this lis-tening to and observing a teacher “on the spot” is refreshingand engaging, and invites them to follow along and partici-pate in problem solving. The teacher can use these same dem-onstration opportunities to model correct and safe labprocedures, thus saving class time and promoting studentinvolvement in lab work.

At the other end of the cognitive scale, demonstrationsprovide students with opportunities to develop crucial higherlevel thinking skills such as analysis, characterization, evalu-ation, and synthesis. Observing an unexpected event promptsstudents to wonder, to ask questions, to investigate, and todraw conclusions that explain what was observed (4). Per-sonal meaning evolves from such inquiry when students rec-oncile what was observed with past personal experience (12).This is especially important in learning abstract principles ofchemistry and related mathematical symbolism (13). This en-hanced learning has been related to significant improvement

in student achievement when compared to similar settingswhere demonstrations were not conducted (14).

Finally, demonstrations help teachers to assist strugglingstudents to develop problem-solving skills. How? By usingpersonal observation and experience to build a frameworkof key ideas and concepts. Such a “big picture” gives orderand meaning to detail and frees minds to consider what isbeing observed. This “freedom” encourages students andteachers to work together in asking questions and seeking so-lutions, thus evading two time and energy consuming im-pediments to real teaching and learning: the blind acceptanceof textbook explanations (15) and the downloading upon stu-dents of disconnected details that choke problem-solving at-tempts in embryo (12).

Planning a Demonstration

Planning determines whether a demonstration will betrivial and entertaining or an effective learning experience.Planning begins by identifying the intended academic pur-pose, clearly determining what students need to learn, andhow this might be done in the most appropriate and engag-ing way. This planning sequence is a crucial professional judg-ment too often slighted by novice teachers.

A clearly determined academic purpose guides theteacher through the next professional decision: selecting ademonstration from the many available that addresses theconcept being considered, is interesting, is appropriate forthe age and experience of students, is repeatable (since mostchemistry teachers conduct several classes each day), is safe,and is reasonably simple and inexpensive to perform (16).Discussion with peers, access to helpful resources, and com-mon sense will help novice teachers learn to comfortably makethis important determination.

Once a demonstration has been selected, the teacherneeds to consider how best to link it to students’ previousexperiences in a manner that will prompt student thinkingand questioning (17). Performing the demonstration at leastonce before presenting it to students provides opportunityto consider how best to create these links while achieving theacademic purpose of the demonstration. At the same time,this practice run also allows the teacher time to determinethe most effective presentation with options ranging from asilent demonstration with students allowed to wonder whatis happening to a presentation involving several students as-sisting in performing various steps. This rehearsal also helpsto spot problems, streamline the procedure, consider helpfulquestions and how to involve students as much as possible,and identify and address potential safety problems (18).

Conducting a Demonstration

Thorough preparation allows the teacher to focus uponthe students while presenting the demonstration and guid-ing the learning experience. Student learning is enhancedwhen the teacher heeds showmanship principles such as gain-ing the attention and being easily seen and heard by all, “ham-ming it up” or feigning ignorance, involving as many studentas possible, and monitoring the pace of the activity. Attend-ing to these principles adds fun and energy, reduces the chanceof accidentally embarrassing a participant, and focuses atten-

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tion upon the academic purpose. Students have shown moreability to recall and apply a demonstration’s key conceptswhen actively involved in these ways (19).

Follow-Up

The learning value of an effective demonstration is so-lidified by class discussion that summarizes and clarifies whathappened, why it happened, what chemistry principles wereinvolved, and how these principles influenced the observedresults. Often minimized by novice teachers, this discussionis vital to students who learn globally, relying on integrationand consistency of concepts to create meaning. Studentsshould be encouraged and helped to relate the demonstra-tion to familiar real world processes and events of personalinterest. During this discussion time, the teacher should,rather than seek to impress, take great care to ensure that allsubject-related jargon and symbolism is clearly defined andis consistent with the students’ level of chemistry sophistica-tion (20). Demonstration materials should then be storedsafely for future use along with a materials list, a printed pro-cedure, and notes about past use and recommendations.

Sample Demonstration: Shell Game

A simple demonstration, which invites students to thinkabout what they observe, was developed locally for use bystudent-demo teams to promote high school science andchemistry programs. This demonstration has also been de-veloped elsewhere in other formats (21). This demonstrationincorporates the qualities of an effective demonstration pre-viously outlined: a specific academic purpose, use of com-monly available materials, student engagement, links toprevious student learning and experience, showmanship, anda post-demonstration discussion. The academic purpose ofthis demonstration is to introduce and explain the role ofindicators in distinguishing between acids and bases and toreaffirm in students’ minds the principle of conservation ofmatter. This demonstration, using common materials, allowsthe teacher to “play dumb” as students move together throughan episode of outguessing the teacher (which students enjoydoing), culminating in a striking moment of perplexity, andthen to collaboration to determine what “went wrong”. Stu-dent questions and group discussion come naturally and fol-low-up assessment helps determine whether the educationalpurpose of the demonstration has been achieved. This dem-onstration will serve as a concrete referent to underpin moreabstract conceptualization.

Materials

Phenolphthalein indicator solution

Sodium polyacrylate (4 g)

Vinegar (10 mL)

Ammonia (5 drops)

Water (10 mL)

Microtip pipet (2)

Graduated cylinder (50 mL)

Test tube (5 mm × 125 mm, minimum size)

Paper or plastic cups (9 or 12 oz, cups must have a whiteinterior)

Baby diapers (Pampers or Luvs, lining is the source ofsodium polyacrylate)

PreparationShortly before the demonstration begins, do the follow-

ing. Have student assistants help with the preparation:• Fill one pipet half full with ammonia and one pipet

with phenolphthalein.

• Pour into the test tube 10-mL water and 5 drops ofammonia.

• Place 2 or more drops of phenolphthalein into the testtube to produce a bright pink solution. (Add as manydrops as needed to get a bright pink color.)

• Into one cup, add 10-mL vinegar and 5-mL water. Thisis Cup 3.

• Pour 4 g of sodium polyacrylate into Cup 3. Quicklyand gently swirl the cup to form a level surface of so-dium polyacrylate. Practice this a few times. It is im-portant that the sodium polyacrylate is level in the cup.The leveled sodium polyacrylate will appear as the bot-tom of the cup.

Procedure

1. Place a table where all students can see and be as closeto the demonstration as possible. Have the ammonia,vinegar, indicator, water, and baby diaper on the table.Tell students these are involved in the demonstrationthat they are going to see. Ask them to identify theseitems by appearance and smell. (You can have fun withthe baby diaper.) Ask: How are they similar? Differ-ent? How are they used at home? How can you tellthe clear liquids apart? (By smell.) How else? Intro-duce the indicator phenolphthalein and explain thatit is a base indicator (pH 8.2–colorless to pH 10.0–pink) and used to be the active ingredient in Exlaxtablets (because it is suspected to be a carcinogen,phenolphthalein has been replaced with sennosides).Show how the indicator distinguishes between vinegarand ammonia (acid and base). Then, pour water intoa baby diaper to show how the sodium polyacrylatewill absorb water (up to 800 times its weight) and isthe active ingredient in the diapers. Have studentsidentify other uses of water-absorbing compounds(desiccant packets used to keep moisture out of ma-chine parts, photography equipment, food storage,etc.).

2. Set out all three unmarked cups in a row from left toright, with Cup 3 on the right.

3. Hold up the test tube with the pink solution so every-one can see it. Pour the pink solution into the cup onthe far left (Cup 1). Ask the students what they justsaw. This encourages a sense of confidence and helpsset them up for what is coming.

4. Shuffle the cups around, and then ask students to guesswhich cup contains the solution. Have fun with thisand involve all students. Hold up the cup they choose

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so they can see when they are correct. Ask students whoguess correctly how they were able to get the right cup.

5. Quickly shuffle the cups again.

6. Ask the class which cup contains the pink solution.For fun, put some students on the spot to guess. Whenthe class finally determines which cup it is, raise thecup and pour the solution into Cup 2 (the empty cup).

7. Repeat steps 3–4 a couple of times. You will be pour-ing the pink solution back and forth between Cups 1and 2. Students will enjoy trying to follow and guesscorrectly. Their confidence in guessing where the liq-uid is will soar as they practice following your shuf-fling motion. Look around the room to see that allare involved and that pacing is appropriate.

8. Now pour the pink solution into Cup 3.

9. As you shuffle the cups, look into Cup 3. The vinegarshould have lowered the pH below 8.2 and caused thesolution to turn clear, be absorbed by the sodiumpolyacrylate, and blend in with the white interior ofthe cup.

10. Now ask the class to guess again which cup containsthe pink solution. As before, hold the chosen cup upso students can see into it. Turn the cup over slowlyon the table. Students will be surprised that no liquidpours out. Repeat this with the remaining two cups.Students will be baffled that the pink solution is“gone”. Stack cups on one other.

11. Ask the class what happened. Students will quicklyblurt out that teacher cheated or deceived them some-how. Other, more insightful explanations will gradu-ally emerge. Students who were acknowledged forbeing correct before will work hard to explain whathappened. Have a student write all reasonable expla-nations on board.

12. When you feel the time is right, use student commentsand hints to the class to link properties of the materi-als involved to what happened. Discuss the use of theindicator, pH relationships, and how the apparent dis-appearance of the liquid can be explained. Don’t saytoo much; let students have the spotlight as the mys-tery is unraveled.

To help students deepen their understanding, ask stu-dents to summarize what has been discussed regard-ing pH, acids, bases, and indicators. Have studentspredict whether common liquids are acids or bases, andthen have them use the indicator to confirm their pre-dictions. Try the same procedure with a couple of “un-known” liquids. When students seem to clearlyunderstand, have students write a short paragraph de-scribing and explaining what they saw using the termspH, acid, base, indicator, and conservation of matter.Read a couple of the paragraphs out loud and ask theclass if the written statements captured what the classhas been considering.

Hazards

Phenolphthalein is a suspected carcinogen. It is still safeto use as an indicator in this demonstration if used prudently.

Avoid exposure to skin. If it contacts skin or eyes, wash withcopious amounts of water (22).

ResourcesTeachers today have convenient access to an abundance

of demonstration ideas such as the one just considered, andthey are available in a variety of formats. Textbook publish-ers supplement modern texts with demonstrations inserts,provide lab and demonstration manuals, and make availableCD-ROM and videotape presentations of demonstrationsthat are dangerous or otherwise difficult to perform in class-rooms. In addition, professional and education journals regu-larly feature creative demonstrations and publish ideas fromstate, regional, and national professional conferences, andmake available collections of demonstrations in print and elec-tronic form. For example, the Journal of Chemical Educationmakes available CD-ROM collections of demonstrations, onecalled the General Chemistry Collection and another calledChemistry Comes Alive (23). Supplementing these resources,a number of authoritative handbooks combine hundreds oftested demonstrations into conveniently formatted volumes(24).

In recent years, the number of electronic sources ofchemistry demonstrations has exploded. A simple search forchemistry demonstrations will yield dozens of sites main-tained by universities, professional organizations, public andprivate schools, and private organizations (25).

ConclusionTeachers need to communicate the story and excitement

of discovery in chemistry. Our current human conditionshows our great need to explore new ideas and to developpersonal meaning based upon enlightened thought. By us-ing demonstrations in appropriate and thoughtful ways,teachers will teach better, inspire more, and increase the like-lihood that chemistry will contribute to a better future forall of us.

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Teacher Preparation, Standard 3: Inquiry. http://www.nsta.org(accessed Dec 2002).

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3. Lomax, J. J. Chem. Educ. 1994, 71, 428–430.4. Moore, J. J. Chem. Educ. 1999, 76, 877.5. Golstaneh, K. Coll. Sci. Teach. 1998, 27, 356–359.6. Hubisz, J. Grant #1998-4248: Review of Middle School Physi-

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7. Martin-Hansen, L. The Science Teacher 2002, 69, 34–37.8. Clark, B. Growing Up Gifted, 3rd ed.; Merrill: New York, 1988;

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14. Bowen, C.; Phelps, A. J. Chem. Educ. 1997, 74, 715–719.15. Walpole, S. Read. Teach. 1999, 4, 358–369.16. Trowbridge, L.; Bybee, R.; Powell, J. Teaching Secondary School

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17. Kelter, P. J. Chem. Educ. 1994, 71, 109–110.18. Moore, J. J. Chem. Educ. 2000, 77, 429.19. Waldman, A.; Schechinger, L. A. J. Chem. Educ. 1996, 73,

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23. For ordering information contact JCE Software at the Universityof Wisconsin–Madison: online at http://jchemed.chem.wisc.edu/

JCESoft/index.html (accessed Dec 2002).24. (a) Tested Demonstrations in Chemistry; Gilbert, G.; Ayea,

H.; Dreishach, D., Eds.; Journal of Chemical Educationand Division of Chemical Education, Inc., AmericanChemical Society: Easton, PA, 1994. (b) Lister, T. ClassicChemistry Demonstrations; Education Division, Royal So-ciety of Chemistry: London, 1995. (c) Shakhashiri, B.Chemical Demonstrations: a Handbook for Teachers of Chem-istry; University of Wisconsin Press: Madison, WI, 1983.(d) Summerlin, L.; Ealy, J. Chemical Demonstrations: aSource Book for Teachers; American Chemical Society: Wash-ington, DC, 1985.

25. (a) Journal of Chemical Education Online Home Page.http://jchemed.chem.wisc.edu (accessed Dec 2002). (b) ScienceIs Fun Home Page. http://scifun.chem.wisc.edu (accessed Dec2002). (c) Tested Demonstrations Home Page. http://faculty.kutztown.edu/vitz/TD/TDhome.html (accessed Dec 2002).