edited by RICHARD STEINER University of Utah
chemi~tryfor kid/
Salt Lake City. UT 84112
Pop-and-Sniff Experimentation A High-Sensory-Impact Teaching Device Emeric Schultz Bloomsburg University. Bloomsburg, PA 17815 I t is generally recognized that there is a strong need to promote the development of thinking skills at all levels of education. This is especially the case a t the elementary level where most learning is by rote. Scratch-and-sniff pads are used widely by teachers as reward devices because of their universal appeal to children. I t occurred to the author that scratch-and-sniffs could he "subverted" to teach thinking skills to students. This can he accomplished by using commonly found polyethylene packing material with the trade name Bubble Pakl (Fig. 1).When pressed with the fingers or when stepped upon, i t gives a characteristic popping sound. If scented material could he incorporated into the Bubble Pak, it would he released with the popping and thus simulate the microencapsulation that exists in scratch-and-sniff stickers. Conslructlon of Modlfled Pop-and-Sniff The scents associated with bananas, pineapples, and cinnamon work well since their respective compounds, amyl acetate.. ethvl . butvrate, and trans-cinnamaldehvde are liquirl, at room tem&ature and have h i ~ hvapor pressures. i n the quantities that arr used, all thrre rhemicalsare safe.'l'he banana is an especially good choice due to its universal appeal to children and its unique fragrance. The various chemicals are injected into the Bubble Pak from the hack (flat side) by the use of a disposable 10-mL plastic syringe with a 20-gauge needle; one drop is sufficient. The bubble is then filled with air by using a 50-mL syringe with a 20-gauge needle. Once the bubble becomes turgid, the needle is withdrawn and hot "ski wax" is applied to the puncture hole to seal the bubble. Normal paraffin is too brittle when it dries and therefore will peel off easily, expose the hole, and leak the contents. Blue or purple cross-country ski wax is ideal. The fact that the dot of wax shows is actually an advantage that can be educationally exploited. Injection of amyl acetate or ethyl hutyrate result in a modified pop-and-sniff that is indistinguishable from the unaltered material except that the wax seal shows; the liquid completely vaporizes within the bubble. The trans-cinnamaldehyde will, on the other hand, develop a tan deposit inside the Buhhle Pak upon storage. Figure 2 shows a section of Bubble Pak containing amyl acetate. With a drop of the appropriate chemical added, small pieces of freeze-dried bananas and pineapples can also be incorporated into the Bubble Pak through a slit cut in the back side. The slit is sealed with Scotch Magic2 tape. Again, the 50-mL syringe is used to reinflate the Bubble Pak and
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Manufactured by Gafcel Industries. Inc.. 220 East 134th Street, New York, NY 10451. Manufactured by 3MlCincinnati Branch. 4835 Para Drive. Cincinnati. OH 45237.
Ftgure 1 . A sectlo" of polyethylene packing
Figure 2. Amy1 acetate being
material, i e , bubble plastic
injected into a CellI of bubble plastic
the hole is sealed with wax as previously described (Fig. 3). The "doctoring" of the freeze-dried slices is necessary since freeze drying removes much of the appropriate odor. Classroom Use of Modified Pop-and-Snlff This modified pop-and-sniff was initially used with third through fifth grade students who were studying "What is a smell?" The general approach used is outlined below: Volume 64
Number 9
September 1987
797
Figure 3. Sealing the punctured cell ot bubble plastic with wax.
Figure 5. A section of bubble plastic containing amyl acetate
7. Presentation of pop-and-sniffwithamyl acetate inside (Fig. 5):
When the bubbles arepopped, the children smell hananas, but there are no bananas present. We discuss how this is possible. Then someone usually guesses how the modified pop-and-sniff is made. Finally the method is shown. 8. Presentation of two mystery pop-and-sniffs: Pop-and-sniffs containingthe smells of cinnamon and pineapple are presented consecutively. Someone mentions the correct smell and everyone else quickly agrees. 9. Discussion of what is a smell: Students come to the recognition that a smell is caused by some things that travel through air. The words gases and molecules can he introduced or reinforced.
Figure 4. A section of bubble plastic containing banana slices.
1. Presentation of scratch-and-sniffs. 2. Inquiry as to how the scratch-and-sniffs work: A working hypothesis that is very close lo the real explanation can beelicited
from the students. 3. Presentation of a large, unaltered pop-and-sniffwith the question, "For what animal would this he a scratch and sniff?" The
invariable response is "an elephant". 4. Discussion of the concept of models: Several models, including ball-and-stick chemical models, are presented to the students. One must place emphasis on the fact that each model i8 a
remesentation, in fact, an imperfect representation of the real thing. 5. Presentation of bananas: "What do hananas smell like?" "What would happen if we scratched a scratch-and-sniffthat had a banana pictured an it?" Discussion ensues as to why and how we smell. 6. Presentation of pop-and-sniffs with banana slices (Fig. 4): There is an explanation as to how these are made. Popping of bubbles gives the expected results.
798
Journal of Chemical Education
Evaluation of Pop-and-Snlff Pop-and-sniffs generate quite a bit of excitement. Students love to pop them and then guess the smell. A psychologist friend opined that the reason for the intense interest in being involved is due to Pop-and-Sniff having high sensory impact: visual-the bubbles before and after; audio-the popping sound; tactile-the breaking of the bubble; olfactorv-the smell of the contents. In addition. there is a sense of mystery that arouses curiosity. This intense interest should not he sacrificed to a s i m ~ l e show-and-trllformat.Thr srudent must hein\,olved ncti\,f4y in the DTO(.ESS. 'I'he anticil)ntion and hirh nttrntion level can he used to teach important concepts, most importantly the nature of models and how they can be used to explain certain phenomena. When vop-and-sniffs are used in an inteprated, multiperiod for& the results are extremely encouraging. The quality of student written results is testament to the attention students have given. These written reports further indicate that many students, a t least a t the fifth-grade level, are quite capable of expressing themselves comfortably in abstract terms. Any methodology that supports this useful preparation for future learning needs to be encouraged and developed further.
