4 4 Nov /Dec 2003s c i e n c e s c o p e

Dear Eighth Graders,Thank you for sharing your fantastic demonstrations. Wethought touching slime was awesome! We also enjoyed see-ing the baking soda and vinegar blow the cork out of thesoda bottle all the way up to the ceiling. We were surprisedto learn that flames have different colors when chemicalsare added. Setting the dollar bill on fire was cool. Thankyou for preparing and sharing your experiments with us.Sincerely,Mrs. Jones Third Grade Class

When my eighth grade students read this letter, they werefilled with a sense of pride and accomplishment, and Iwas pleased that our Demo Day had been a success. OnDemo Day, my students perform and explain science dem-onstrations they have researched to a group of youngerstudents. By assuming the role of teacher, my studentsgain valuable research and presentation skills, learn howto teach science to younger students, and experiencelearning from the front of the classroom.

Pre-demo planningAs soon as you know when you’d like to hold your DemoDay, contact the teacher of the other class or classes thatyou’d like to invite so you can work out a schedule. Thiswill also give the teachers time to incorporate Demo Dayinto their curricula. They may wish to review some of thebasic science that will be covered, so tell them which dem-onstrations your students will be performing as soon as

they have been approved. Also, make sure you haveenough safety goggles for your visitors, if they arerequired.

Three weeks before Demo Day, I divide students into groupsof two or three to begin the research process. Having smallergroups helps ensure that everyone participates. Each groupconducts background research to find an appropriate demon-stration and make it accessible to a third grade audience.Choosing their own demonstrations gives my students a senseof ownership over their project. To help students choose anappropriate project, I provide the following guidelines:

• The demonstration must be safe for the student and theaudience and require no hazardous materials.

• It must be simple enough that the student can set up andperform it in three to five minutes.

Daniel Heller, a former middle school science teacher, currently worksas a researcher and teaching assistant in the chemistry department atthe University of Illinois, Urbana-Champaign campus.

• It must be “cool” enough that third graders will think itis interesting.

• All safety protocol must be spelled out, including anyprotective equipment that is needed.

• The student must be able to explain the science behindthe demonstration to third graders so they can under-stand what is happening.

I provide 20 to 30 minutes of class time over one ortwo days for students to find suitable demonstrations.Students use various sources for information, such as booksby Janice VanCleave and Mister Wizard, and pre-screenedsites I located with an Internet search engine (such assmartweed.olemiss.edu/nmgk12/curriculum/elementary/fourth/Dry_ice/presentations/dryice_demos.doc) to find dem-onstrations that interest them. Students can conduct ex-tra research on their own if they can’t find something thatcaptures their imagination. Once a group has identified a

samplerS C I E N C E

Teacher for a day: Sometimes the front of theclassroom is the best place to learn

On Demo Day, my students perform and explain sciencedemonstrations to a group of younger students.

PH

OTO

S C

OU

RT

ES

Y O

F A

UT

HO

R

4 5Nov /Dec 2003 s c i e n c e s c o p e

few possible demonstrations, they list them in order ofpreference and submit the list to me for approval.

I approve demonstrations that meet the criteria mentionedearlier, and steer students toward simpler, more accessible dis-plays for third grade students. Often a student will choose ademonstration that is too subtle for younger students, or thedemonstration he/she has found in a book will take too longto prepare. While students are looking for demonstrations,they are instructed to choose three or four possibilities thatlook interesting to them. The group shows me its list of possi-bilities and I will usually explain which of them are most prom-ising. These include chemical reactions, such as combiningbaking soda and vinegar, and making various types of slime;physics demonstrations, such as picking up pieces of paperwith a balloon and bending of a stream of water with staticelectricity; and other safe but exciting displays.

Assessment and rehearsalAfter I approve one demonstration for each group, studentsbegin three short writing tasks: a list of required materials,the procedure in their own words (in the format of a com-plete, numbered list), and a simple explanation (usually aparagraph or two) of the science concepts (see Figure 1). Iallow students to submit rewrites after I critique and gradetheir assignments, which helps them boost their grade andperfect their presentation plan.

To assess the assignments, I look for evidence that stu-dents followed directions, wrote a complete and accurate

FIGURE 1 Sample student demonstrations

Air pressure magicMaterials• baking soda• vinegar• bottle (not glass)• paper towel• cork with streamers attached• safety goggles

Procedure1. Put baking soda into rolled paper towel.2. Put 120 mL of water and 120 mL of vinegar in bottle.3. Put paper towel in bottle.4. Put cork with streamers in bottle.5. Stand back and watch it pop.

ExplanationThe baking soda reacts with the vinegar to producecarbon dioxide gas. When the bottle pressure gets highenough from filling with gas, which compresses the air,the cork pops off and shoots upward.

Sodium polyacrylate—The diaper polymerMaterials• water• sodium polyacrylate• paper cup• glass beaker

Procedure1. Put sodium polyacrylate into paper cup.2. Pour water into cup.3. Place cup overhead and tip it as if you were going to

pour the water on your head.4. Repeat demonstration using beaker instead of paper

cup so students can observe the reaction of the waterand sodium polyacrylate.

ExplanationSodium polyacrylate, which is used in diapers, canabsorb large amounts of water (almost 800 times itsown weight). Just a small amount of this amazingpowder can turn an entire cup of water into a gel. Thisonly takes a few seconds.

samplerS C I E N C E

procedure and materials list, and provided a conclusiveexplanation suitable for a third grade student. If one ofthe requirements needs a substantial amount of revision,I hand the assignment back for corrections. Most groupsrequire one or more revisions in order to compose an ex-

Hands-on demonstration are very popular with a younger audience,especially when slime is involved.

4 6 Nov /Dec 2003s c i e n c e s c o p e

planation suitable for a third grade audience. My studentssurprise me, however, in their ability to assimilate newinformation and explain it in a manner that younger stu-dents can comprehend.

When the writing assignments are complete, students be-gin to prepare and practice their demonstrations over thecourse of a week. I provide a few simple materials, such aspans and beakers, and any pre-approved chemicals such assodium polyacrylate, the super absorber, which they wouldhave difficulty obtaining on their own. Students must sup-ply any other materials needed for their demonstrations.

To ensure that students are ready by Demo Day, I pro-vide a total of 45 minutes of class time during the weekfor individual demonstration and explanation practice,15 minutes at the end of three consecutive classes. Wethen use a 40-minute class period on the day precedingDemo Day for a dress rehearsal.

The rehearsal is an enlightening experience for studentsand teacher alike. Each group performs and explains its dem-onstration to the class. In doing so, each student acquiressome hands-on teaching time and public speaking experi-ence. Although presenting in front of one’s peers can be in-timidating, the public nature of the rehearsal provides greatmotivation for students to make a serious presentation andattempt to explain the demonstration clearly. Student pre-senters receive constructive feedback from the teacher andpeers on how well they communicated their explanations.

Show timeIn each 40-minute class period, smiles abound as groupsbring their demonstration to the front of the room, share

samplerS C I E N C E

it with their audience, and explain the science to thethird graders. The younger students are delighted by themassive amount of bubbles created by dry ice, the bal-loon blown up by the reaction of vinegar and bakingsoda, their hands-on encounter with polyacrylate slime,and all the other attention-grabbing demonstrations per-formed by students.

On average, you can squeeze eight student presentationsinto a 20-minute demonstration period. Afterward, the thirdgraders split into small groups and visit with the presenterswho are stationed at lab tables around the room. This givesyounger students a close-up, hands-on experience with thepresenters. It also allows my students more time to demon-strate and explain in a more relaxed environment. Theyounger students can also try some of the simpler demon-strations, such as bending a stream of water with static elec-tricity, or blowing air across the mouth of a straw immersedin water to demonstrate Bernoulli’s principle.

ResultsWhen interacting with younger students, I find that myclasses take their role as teachers seriously. This includesexhibiting a conscious restraint on immature behavior.When given a chance to be “the adult” in a situation,students rise to the occasion. Besides the obvious fun thatall students have on Demo Day, the demonstrations pro-mote a type of student-centered learning that is more ef-fective in engaging learners than almost any other teach-ing style I have used. Student-run demonstrations pro-mote interdisciplinary learning that does not usually oc-cur in science class or middle school. When eighth gradestudents learn a concept, go through the process of put-ting that concept into words that a younger student canunderstand, and subsequently demonstrate it, the conceptis mastered in depth.

Teaching adds new meaning to the familiar proverb: I hearand I forget. I see and I remember. I do and I understand. Byteaching and preparing beforehand, students gain experiencethrough all three learning styles. I believe middle school stu-dents should have this experience, as it helps to bring themout of the self-centered world that most of them inhabit.

AcknowledgementsDeborah Veselka, Science Department Chair of The KinkaidSchool, devoted her valuable time and infinite wisdom tothe development of this activity. Thanks also to NonieHarcombe, Associate Director of the Center for Educationat Rice University, for her editorial support.

Audience enthusiasm bubbles over when the younger students areallowed to try the demonstrations for themselves.