Presenting Effective Demonstrations
"Surprise, humor, and truth are the servants of a good lecturer" - Hubert Alyea
The 5 P's -- Prior Practice Prevents Poor Presentations - Fred Juergens
Chemical Activities, Teacher Edition, Christie Borgford and Lee Summerlin, published by the American Chemical Society.
String & Sticky Tape Experiments, R.D. Edge, published by the American Association of Physics Teachers.
Any of the Books by Mr. Wizard (Don Herbert) especially Supermarket Science.
Teaching Elementary Science, William and Mary Esler, often used as a textbook in Elementary Science Methods courses, may be in your district's professional library.
Science and Children, This is the official NSTA journal for elementary school teachers. It is available by joining the National Science Teachers Association (NSTA). Their other journals are The Science Teacher (designed for high school teachers) and Science Scope (designed for middle school/junior high teachers).
Flinn Scientific Inc., P.O. Box 219, Batavia, IL 60510-0219, 1-800-452-126
This catalog is a must!! Flinn is a family owned company whose only business is to supply schools with chemicals and equipment. Their catalog is an excellent reference book, they offer great products, have fast delivery, plus they always send along a Flinn Goodie Bag with lots of freebies (actually that's not true, one time they left it out, however a quick phone call and one was on its way). Some of their products cost a little more, but believe me the extra expense is worth it! (My personal favorite supplier.)
American Chemical Society, Distribution Office, Dept. 303, P.O. Box 57136, West End Station, Washington, DC 20037 1-800-227-5558
The ACS is the professional organization in chemistry. They have members in industry, government, and education. Most of their publications are of a professional nature, but their education division has some appropriate materials.
Lab Safety Supply, P.O. Box 1368, Janesville, WI 53547-1368, 1-800-356-0783
These folks have everything you would ever need in the way of safety. They have things to solve safety problems you never even knew existed! They also carry laboratory equipment.
TOPS Learning Systems, 10970 S. Mulino Rd., Canby OR 97013, 1-888-773-9755
Science with Simple Things! They have wonderful hands-on activities for sale at very inexpensive prices. I would buy something from them, but I haven't been able to use all the free things they sent me yet! Email them at topsideas@yahoo.com and request a subscription to TOPS Ideas, their catalog/magazine (U.S. addresses only). They have a philosphy I have adopted for my own:
Q: How many science teachers does it take to change a light bulb?
A: A bazillion science teachers can read, or lecture, or theorize about changing a light bulb. But it just won't happen until one actually does it, hands-on.
Capital Microscope Services, 7140 Thimblewood Way. Columbus, GA 31904, 706-576-4132
Get your copy of Larry Banowsky's newsletter by emailing him at banowsky@knology.net
Fisher Scientific, 485 South Frontage Road, Burr Ridge, IL 60521, 1-800-955-1177
Another full line science supplier
VWR Scientific Products/Sargent-Welch, P.O. Box 5229, Buffalo Grove, IL 60089-5229, 1-800-727-4368
Owned by the same company that owns Science Kit & Boreal Labs. They have it all.
Frey Scientific, 100 Paragon Parkway, Mansfield, OH 44903, 1-888-222-1332,
Owned by the Beckley Cardy Group (ask your librarian - she will know who they are). Another full line science supplier
(With apologies to Flinn, Science Kit, Fisher, etc...)
Chemical |
Common Name or Substitute |
Source |
Comments |
| Acetic Acid | White vinegar |
Grocery |
3-4% acetic acid |
| Acetone | fingernail polish remover |
Grocery, drug store |
Flammable |
Aluminum Sodium Sulfate |
alum |
Grocery, drug store |
used in pickling |
| Ammonia | household ammonia |
Grocery, drug store |
solution in water |
Ammonium Chloride |
sal ammoniac |
Drug store |
|
| Ascorbic Acid | Vitamin C tablets |
Grocery, drug store |
use unflavored tablets |
| Boric Acid | Grocery, drug store, hardware |
used to kill roaches | |
| Calcium Carbonate | limestone |
found in rock | |
| Calcium Chloride | Hardware, auto parts |
used to melt ice | |
| Calcium Oxide | quicklime |
Hardware |
used to make mortar |
| Calcium Sulfate | Plaster of Paris |
Hardware |
|
| Carbon | graphite, charcoal |
Grocery, drug, hardware |
"lead' in pencils |
| Carbon Dioxide | dry ice |
Ice Cream Shop |
alka-seltzer in water |
| Carbonic Acid | club soda |
Grocery |
|
| Citric Acid | Grocery |
||
| Copper sulfate | blue vitriol |
Hardware,Farm Supply |
Toxic |
| Ethanol | ethyl alcohol, PGA, grain alcohol |
Liquor store |
100 Proof is 50%, denatured @ drug store, hardware, grocery |
| Glucose | grape sugar |
Grocery |
|
| Glycerol | glycerine |
Grocery, drug store |
|
| Hydrochloric Acid | Muriatic acid |
Hardware Store | used to clean brick |
| Iodine | Grocery, drug store |
Tincture is Iodine in alcohol | |
| Isopropanol | Isopropyl alcohol |
Grocery, drug store |
70% in water, toxic if swallowed |
| Magnesium Hydroxide | Milk of Magnesia |
Grocery, drug store |
water solution |
| Magnesium Sulfate | Epsom salt |
Grocery, drug store |
|
| Methanol | Wood alcohol, Methyl alcohol |
Hardware |
Toxic |
| Naphthalene | Moth balls |
Hardware, grocery, drug store |
certain types only |
| Oxalic Acid | Hardware |
Very toxic, bleaches wood | |
| Phenolphthalein | Ex-Lax |
Grocery, drug store |
Found ONLY in old formulations |
| Potassium Hydrogen Tartrate | Cream of Tartar |
Grocery |
|
| Potassium Nitrate | Saltpeter |
Drug store |
|
| Potassium Sodium Tartrate | Rochelle salt |
Drug store |
|
| Sodium Bicarbonate | Baking soda |
Grocery |
|
| Sodium Carbonate | Washing soda |
Hardware, grocery |
|
| Sodium Chloride | Table salt |
Grocery |
use Kosher salt |
| Sodium Hydroxide | Lye |
Grocery |
Toxic |
| Sodium Hypochlorite | Chlorine Bleach |
Grocery |
|
| Sodium Silicate | Water Glass |
Hobby shop, drug store |
Used to dehydrate flowers |
| Sodium Sulfate | Galuber's salt |
Drug store |
Used in dyeing |
| Sodium Thiosulfate | Hypo or photo fixer |
Photo shop |
|
| Starch | Corn starch, laundry starch |
Grocery |
|
| Sucrose | Sugar |
Grocery |
|
| Sulfur | Flowers of Sulfur | Drug store, grocery |
|
| Sulfuric Acid | Battery acid |
Auto parts store |
Will damage skin, bleach |
| Trisodium Phosphate | TSP |
Hardware, grocery |
Cleaner |
| Water | Distilled water |
Grocery |
Do not use spring water |
| Zinc | Drycell battery containers |
Grocery, hardware, drug store |
Try independent stores first - so many of the chains (particularly the drug stores) only carry fast selling items and will not carry these. Or maybe you can persuade the store to special order the item for you.
To see how many drops of water can be put on the flat surface of a penny.
One eyedropper, beaker of water, paper towel
How many?
Allow students to do this without any suggestions. When they finish have them make suggestions about things they could vary (variables) to compare the number of drops (i.e. heads or tails, height of dropper, size of drops, type of water, etc...). Have them do the procedure 3 times and average the results.
1 Potato
1 Brazil nut or walnut
Make a "candle" out of a potato by using a knife or a cork borer. Slice the nut to make a "wick". Bring this out
with about 5 minutes left in the class period. Tell the class to write down as many observations as they can. Light the
"candle" and allow them to record their observations, from a distance, for about 4 to 4 and a half minutes. If you have
timed this right you will have less than a minute left. Now, eat the candle (or at least take a bite of it) and walk out of the
room.
The next day you can point out the difference between observation and inference. Explain how new observations
constantly lead to changes in science. Science is in a constant state of change.
You know we live at the bottom of an ocean of air. Air exerts pressure on us and everything around us. At sea level the air pressure is 14.7 pounds per square inch or 1 atmosphere. To see this air pressure first hand we have the following demo that can be done any number of ways.
Put about 100 ml of water into a (this part is VERY important) previously rinsed 1 gallon ditto fluid or burner fuel can.
Heat this until steam rises out of the can for at least 2 minutes. Remove the can from the burner or hot plate and
immediately stopper it. You can set the can down and wait or being careful not to burn yourself run cold water over the
can. It should begin to collapse within a minute or 2. When the can has completely collapsed, you may carefully heat it
with the stopper in place until it returns to almost full size.
In the interest of full disclosure, I recently received an email from Andrew Milbauer who says he "has a Masters in Science Education through the University of Minnesota and did extensive training in demonstrations with a disciple of Shakashiri." He says:
"The 55 gallon drum (the collapse after being filled with steam) is highly dangerous. In one situation, with Professor Clint Sprott from the UW Madison physics department this demonstration set off alarms within the neighboring blocks. The fire department was called when people heard the noise. It is rather loud and will cause hearing damage. This is best done by videotaping the drum and showing the video tape to your students. Also notify local authorities as they may be tempted to issue a disturbing the peace citation."
Take a previously rinsed 55 gallon drum and put a small dent in the side. Add 1 gallon of water to it. Heat it on a
camping stove or other suitable apparatus (I use a burner that connects to a propane grill tank) until steam rises out of the
drum for at least 10 minutes. While this is heating coat the threads of the screw top with the sealant plumbers use on pipe
joints. After heating turn off the burner and using gloves immediately put the top on as tight as you can. A final
tightening it with pliers is necessary! The drum should collapse within a few minutes. (Make sure and keep all
appendages clear of the can!) I haven't tried to heat the drum back to its original shape because I am leery of shrapnel.
The steam condenses, then turns back into water. There is only a little air in the can to take the steam's place. There is
much less gas on the inside of the can so there is less pressure inside. The air is pushing on the outside with about 15
pounds of pressure per square inch. The cans are not designed to withstand such pressure so they collapse!
The first and most obvious is What happened? Others are: How could we get the can back to its original size and shape
(or at least close)? Should we leave the stopper (or top) on or off when we try this?
1 Lamp cord or extension cord with receptacle removed
2 Nails or paper clips
1 Pickle (Kosher dills seem to work best)
PRECAUTIONS: Since this demonstration uses 110 volt current, it should only be performed by the teacher. The
students should be instructed about the difference between household current (110 volt) and current flowing from a
battery and should be instructed not to try to repeat this demonstration without knowledgeable adult supervision. Be sure
not to touch any part of the circuit when it is connected to the household current!!!
Put the nails in opposite ends of the pickle making sure that they do not touch each other. Attach one wire of
the lamp cord to each nail. Plug the lamp cord into the wall and in a couple of seconds the pickle will begin to glow.
The pickle is a resistor in the completed circuit. The salt solution inside the pickle provides a pathway for the electrons
while the fibrous portion of the pickle provides enough resistance so that you don't blow a fuse (short-circuit).
Why does the pickle glow? Can you get 2 pickles to glow in a series circuit? In a parallel circuit? Why do kosher dills
seem to work better? Why does the pickle only glow at one end? How many pickles can be connected together and still
have 1 glow? Can other substances be substituted for the pickle?
From Mary Chambers, formerly a Science Teacher at Moore Middle School, now a Principal in Nashville, TN
What percent of the class will aquire HIV
Styrofoam® cups filled with water
Two or three Styrofoam® cups filled with a starch mixture
Sexual Behavior cards for students
Test tubes
Iodine
1. Give each student a cup and a sexual behavior card.
2. Give the students with the starch mixture a sexual card that says they have sex with everyone they can talk into having sex.
3. As the students "have sex" they mix the liquids.
4. When students finish socializing, have them pour their liquids into a test tube.
5. Test each solution with iodine. A positive HIV test will turn black.
For further information see The Science Teacher, November 1993.
Are each of the following solutions acids or bases? Can they be ranked from most acidic to most basic
5ml vinegar
5ml Seven-Up
5ml ammonia
5ml backing soda water
5ml distilled water
Cabbage juice
5 test tubes
test tube holder
safety glasses
1. Label each test tube with the proper solution name.
2. Measure 5 ml of each solution and put in the properly labeled test tube.
3. Measure 5 ml of distilled water and add to each test tube.
4. Measure 5 ml of cabbage juice and add to each test tube.
5. Place the test tube you think is the most acidic in the slot on the far left, place the control in the ` center and the other three test tubes in most acidic to most basic order, left to right.
(Students list the order of solutions)
1. What is an acid? Give three examples that are different from the ones that you used in the lab.
2. What is a base? Give three examples that are different from the ones that you used in the lab.
3. What is a pH scale? What numbers are acid, what numbers are base?
1. Remember to have students wear safety glasses.
2. Make the cabbage juice ahead of class, do NOT allow students to use the blender.
3. Caution students about test tubes rolling off the desk. Put them in the test tube holders.
4. NEVER mix chemicals.
Taken from Flinn Scientific "ChemFax"
Have you ever heard of a dust explosion in your area? (see accompaning article) They are rather common in grain elevators, coal mines, and saw mills. A spark, even due to friction or flame, can set off burnable dust in air to produce a large explosion. The smaller the particles, the more surface area is exposed to the oxygen in the air, thus the more explosive the particles. Compare the length of time it takes to ignite each of the following: a log, a stick, wood chips, saw dust, and a powder. When moving from a log to a powder, the rate of combustion increases. Igniting a powder material will cause an instantaneous explosion with a relatively large flame.This demonstration will illustrate the explosive nature of a powder through the construction of a mini grain elevator explosion. A small paint can or coffee can will be used to represent the grain elevator and Lycopodium powder will be used as the dust. This explosion will wake up and fascinate even your most lethargic students.
Lycopodium powder (10 grams or less)
1 quart size paint can with lid
1 Beral pipet (extra large bulb works best)
1 tea candle
1 hammer
1 #10 finishing nail
1 flat head screwdriver
matches or lighter
This should be done as a teacher demonstration ONLY! Read all safety information before trying this demonstration. We urge you to practice this demonstration several times prior to conducting it in front of students.
Use the hammer and nail to punch a hole in the side of the paint can. The hole should be about 1 inch from the top and be about the same size as the Beral pipet stem. Put the can inside the paint can. Fill the Beral pipette by squeezing the bulb and placing the tip of the pipet into the lycopodium powder. While it is in the powder release the bulb. Fill the pipet about 2/3 full. It may take several tries in order to fill the pipet.
Light the candle and put the lid on the can using the hammer. Make sure the lycopodium powder is near the open tip of the pipet, and put the tip of the pipet into the hole in the can. The pipet bulb must be tipped slightly downward (the tip pointed upward) so the lycopodium will be sprayed upward. Do NOT lean over the can. Stand as far back as possible.
Squeeze the pipet bulb. The lid should explode off the can with a loud bang. A flame will shoot out of the can and a sweet smell will fill the air.
If the lid does not fly off, it is because the candle went out. The candle will not stay lit very long when the lid is on the can also the paint can will get very hot, therefore it is best to put the lid on just seconds before you spray the powder into the can. The lid will shoot up and hit an 8 1/2 foot ceiling with great force even if this is done on the floor. You might want to consider doing this outside as this could easily dent soft ceiling material.
If the pipet is tilted downward rather than upward, the lycopodium powder may just put out the flame. You may use flour, corn starch, saw dust, or cinnamon instead of lycopodium powder.
Lycopodium powder is easily combustable when dispersed in air. Be careful not to allow the powder to become airborne. Keep all flammable materials away from the demonstration area. Do not stand over the can while doing the demonstration. The lid will be propelled into the air with great force and a relatively large flame will be produced. Lycopodium may cause allergic reactions. Inhalation and skin contact with the powder should be avoided. Use appropriate personal protection. Wipe up any spilled powder with wet paper towels. Clean the paint can with wet paper towels and dispose of the towels in a waste container. Wash hands thoroughly.
Special thanks to Lee Marek and Flinn Scientific for these instructions.
Will household bleach serve as a catalyst to make a new compound or break an existing compound?
10 ml bleach
50 ml water
250 ml beaker
steel wool
safety goggles
1. Put 50 ml of water in the beaker.
2. Place a small ball of steel wool in the water.
3. Observe and record any changes.
4. Add 10 ml of bleach to the water.
5. Observe and record any changes.
6. Allow to sit for 24 hours, then observe and record any changes.
(Students list the changes they observe)
1. What is a catalyst?
2. In this experiment, what reaction did the catalyst cause?
3. Identify two other catalysts.
4. Why would industrial engineers be interested in the action of catalysts?
1. Remember safety glasses.
2. Caution students to wash off any bleach they may get on their skin.
3. You may want your students to wear safety aprons.
For several years now students have make Slime, Silly Putty, Nylon, Gaak, Gluep and other polymers as part of a physical science or chemistry unit. This activity demonstrates polymerization using two common items. The polymer can then be broken using a saturated sodium chloride (brine) solution.
1% w/v solution Calcium Chloride in water
1 bottle Gaviscon® antacid
Saturated sodium chloride solution
Make a 1% weight/volume solution of calcium chloride by dissolving 1 gram of calcium chloride in 100 ml of water. Calcium chloride is sold to melt snow and ice (Prestone Driveway Heat® is one brand). You can find it at hardware and auto parts stores. Make sure it contains calcium chloride! Gaviscon® can be found at any discount or drug store. One bottle of each of these should last you for years!
Place a small amount of Gaviscon® into the calcium chloride solution and it will form a worm of crosslinked sodium alginate. Add these worms to the saturated sodium chloride solution and they will dissolve and form a cloudy solution.
Copyright © 1998, 2005 Tommy Franklin All rights reserved.