Science Workshop
Science demonstrations
that anyone can do.
Using everyday materials such as balloons and straws, participants will learn
how to perform 25 simple demonstrations. These may be for their students,
their friends or their own children at a party. After each demonstration, the
science concepts that help explain the results will be given.
Presented by John O’Leary
John O’Leary has taught Conceptual Physics, Physics, AP Physics,
Photography and Astronomy both in the US and in Japan. He loves doing
demonstrations that challenge misconceptions in science and promote
understanding.
Demos 1-12: At the dining table
13-15: Using balloons
16-22: Assorted
23-25: Lights out, using flames
At the Dining Table
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1. Balance the salt shaker
Materials: a salt shaker with flat sides with salt inside.
Demo: Balance the salt shaker on it’s edge, using salt crystals to support one edge. Blow
away unneeded crystals.
Concepts: All objects that are in equilibrium have their center of gravity above their base.
In this case, the base is very small, so this is very unstable, any movement will lower the
c of g and it will topple.
2. Balance the Fork & Spoon
Materials: One large fork & one large spoon, matches and a glass.
Demo: insert the fork tines into the spoon so that they hold together. Now insert a match
with the head away from the fork & spoon. Adjust the angle so that when set on the edge
of the glass, it will balance. When the match head is lit, the match will burn down to just
the section needed to be the base for the hanging materials.
Concepts: Again, the C of G is over the base. The match goes out because the glass takes
some of the heat from the wood, keeping the wood from going above the kindling
temperature, so it will not catch on fire. The increased pressure on the wood may also
raise the kindling temperature, hindering it from burning beyond the edge.
3. Balance the bottle on 3 knives
Materials: 3 identical tall bottles, 3 knives and a bottle of water
Demo: Weave the 3 knives to make a triangle shape, then set the bottle of water on the
center.
Concepts: Unattached items can become a rigid structure when pressure is applied to
them.
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4. Hold that water
Materials: a glass of water, slightly over-filled and a square of light cardboard, a little
larger in size than the rim of the glass.
Demo: gently press the cardboard onto the rim, leaving no bubbles underneath and no
gaps. Now turn the glass over gently, the water stays in the glass above the cardboard.
Concepts: The air pressure outside the cardboard is greater than the pressure of the water
pressing down on the cardboard. The air pressure pushes up more than the water pushes
down on the cardboard, so it stays in place.
5. Sliding Straw—The Great Attractor
Material: One straw in it’s paper cover
Demo: rip off one end of the cover and rip that into small pieces onto the table top., Now
gently slide the plastic straw up and down a few times before removing it. Now it will
pick up the paper bits.
Concepts: Some materials easily lose their surface electrons when rubbed. The same
thing is going on when combing your hair with a plastic comb. The hair loses some
electrons and the comb accepts them, becoming charged. The straw has a few extra
electrons on it’s surface that can not leak away, for this plastic is an electric insulator. As
the charged object gets closer, the electric field of the straw causes some electrons in the
paper to move away from the straw, leaving the near surface positively charged. This
electrical attraction, if greater than the weight of the paper bit, will cause the paper to lift
up and be held to the plastic straw.
6. Hanging Spoons on your face
Material: a clean large spoon
Demo: huff a little moisture from your breath onto the inside of a spoon and place it
handle down onto the end of your nose.
Concepts: The attraction of the spoon to your nose should prevent the spoon from sliding
off.
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7. Balancing 3 Coke Bottles
Materials: 3 old Coke bottles made of glass
Demo: gently place the 2nd bottle horizontally onto the bottom bottle until it balances,
then place the 3rd on top of the 2nd vertically.
Concepts: Again, if the C of G is over the base it will not topple.
8. Waiter, please take my table cloth
Materials: a smooth slick cloth, plate, silverware, glasses, etc.
Demo: Pull horizontally and quickly to remove the cloth from under the table setting.
Concepts: the slick cloth will not offer much friction and will smoothly pull out from the
table setting if pulled very quickly, giving the table setting no time to start moving.
Newton’s law of Inertia states that objects at rest tend to stay at rest proportional to their
mass.
9. One order of pre-sliced bananas please.
Materials: fresh bananas, a small needle.
Demo: As you pull back the peel on the banana, you discover that it has already been
sliced.
Concepts: A small needle can easily be inserted in regular intervals and pre-slice the
banana without the hole being detected.
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10. Float please.
Materials: a clean one yen coin and a glass of water.
Demo: if your hands are clean, you can gently lower a one yen coin on the surface of the
water and it will float.
Concepts: The surface of the water acts like a long chain due the attraction of the water
molecules. If the object is not too sharp or too heavy, it will not break the chain and the
coin will be held up on top of the water.
11. Crystal Symphony
Materials: a crystal glass with a little liquid inside.
Demo: wet your finger then slowly and gently rub along the top rim of the glass. Soon a
single sound is heard until your finger gets dry.
Concepts: As your finger moves along the crystal glass, there is some friction. The stick
then slip action causes only the resonant frequency of the glass and liquid to get louder.
Changing the level of the liquid will give different pitch sounds.
12. One long neck musical instrument please.
Materials: One long neck bottle with or without liquid inside.
Demo: Blow across the bottle mouth while putting your lower lip on the bottle’s edge. A
single sound should be heard.
Concepts: This air column is closed on the lower end. Only one sound resonates with this
length and gets louder. If you “over blow”, but blowing very hard a note three times
higher can be created.
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Balloons and other assorted demos
13. Don’t Pop My Balloon
Materials: One balloon, blown up and tied off, a smooth wooden skewer and a touch of
oil or Vaseline lotion.
Demo: Blow up one balloon and push the skewer in quickly from the side, it should pop.
Now lift the 2nd balloon and slowly push in the oiled skewer, picking the part of the
balloon that is not stretched out. It is not being pulled out there but will elastically keep a
tight seal around the skewer as it is inserted into the balloon.
Concepts: The rubber molecules are going to attract, even though they are being pushed
away from each other. Even when punctured, the rubber molecules in the unstretched
areas will not tear apart.
14. Using balloons to move big beams without touching them.
Materials: A blown up balloon, tied off, a thumb tack and a large wood beam.
Demo: balance the beam on a table top on top of the thumb tack. Now rub the balloon on
your shirt or a sweater and when brought close to the wood, it will start attracting it,
causing it to start swinging around it’s pivot point.
Concepts: Again, the negatively charged balloon’s electrical field induces a positive
charge on the wood. The field then attracts the wood towards the balloon. There is very
little friction from the small pin and the force acting at a distance from the pivot provides
a torque which accelerates the board’s rotationally.
15. Getting a balloon into a small jug (then getting it out again!)
Materials: A small balloon filled with water, slightly greased with Vaseline or oil, a
match, a clear glass jug and a small strip of cotton or newsprint.
Demo: Try to force the balloon (or a peeled hard boiled egg) into the jug. It won’t go in.
Then light a strip of paper and toss it into the jug. As it burns out, set the water balloon on
the mouth of the jug and see it move slowly into the jug. To get it out you must invert the
jug and blow under it with a long straw.
Concepts: The heated air in the jug has few molecules than at room temperature. When
the water balloon (or hard boiled egg) is put on the mouth of the jug, no air can get in or
out. As the air inside cools, the pressure drops. The higher atmospheric pressure outside
the bottle forces the water balloon into the lower pressure area, the inside of the jug. To
get the balloon out, you must blow more air into the bottle to create a high pressure area
there. Then the balloon is forced out into the lower pressure air of the room.
Note: This is Mr. Wizard’s (Frank Herbert) favorite demo of all time from his TV series.
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16. Straw Strength: Can it push through a raw potato?
Materials: 2 straight plastic straws and a raw potato
Demo: Try to force the straw through the potato by pushing in the surface slowly. The
straw should collapse. Now carefully jab the straw into the potato as fast as you can. DO
NOT hold the straw into your palm or stick it into your hand! If going fast enough, it
should go through the potato.
Concepts: the fast moving plastic straw acts very rigid and acts as if it were a long solid
tube. It does not have time to collapse. The edge of the straw at high speeds provides a
very high pressure and it plows it’s way through easily.
17. Breaking Boards with Karate
Material: a board cut so that the grain is across the width not along the length, some
books to hold the board off the table top.
Demo: Hold your hand rigidly and quickly use the heel of your hand to strike straight
down onto the board in the middle. It should break apart easily.
Concepts: The hand is a kg or 2 of mass and when moving wants to keep moving. When
it hits the board, it exerts a high force on the board, causing it to move downward. The
board is weaker along the grain lines and it separates there as the hand crashes through it.
18. Zip-lock Bag Collision
Material: fill a small zip lock with water, leave no air bubbles, one sharp pencil.
Demo: Carefully stab the pencil into the zip lock bag. It should go all the way through
without any water leaking out.
Concepts: Again, the plastic (polyethylene) has long molecules which tend to attract to
each other strongly. As one strand is separated from those on the sides, the material tends
to attract as it can as opposed to ripping.
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19. Vacuum hose music
Material: one rippled plastic hose
Demo: swing the hose around your head, one note should be heard. Swing it faster should
produce a higher note. Faster still should give a 3rd and even higher note.
Concepts: The fast end has lower pressure according to Bernoulli’s Principle. Air is
forced in the high pressure end and out the swinging (low pressure) end. On the way
through the rippled hose, many sounds exist, but depending on the length, only one sound
will resonate. The faster the air moves, the higher the frequency sound that resonates.
20. Thinking cap
Materials: one metal coat hanger, 2 old tennis balls, small pliers, small knife
Demo: Cut the coat hanger and bend it into a giant M shape. Now make a small 1-2 cm
loop on ends of the metal M. Cut a small slit in the tennis balls and push the loops into
the slits to hold the tennis balls on the M. Now balance the M on the center of your head.
You can only see one ball at a time. You can rotate to look at the other and the M will
stay in place.
Concepts: Again, objects that are balanced have their c of g above or below their base.
Because the M has inertia, even though your head turns, it tends not to.
21. Tempest in a teapot.
Materials: get a 2 or 3 liter smooth round soda bottle. Fill it almost full with water and
add 2 or 3 drops of liquid soap.
Demo: Spin the water after shaking to get bubbles inside. You should see a tornado
swirling around for a while.
Concepts: The more massive water has more inertia than the air bubbles and tends to stay
on the outside, forcing the less massive, less dense bubbles to the inside. Water in motion
tends to keep moving so the swirling continues for a while. Some call this swirling mass
a vortex.
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Lights Out: Let the flames begin
22. Money to burn
Materials: some paper the size of paper money, paper money, a beaker of water, a beaker
of alcohol, a large empty beaker and matches. A tray should be nearby to catch the ashes.
Demo: Dip the paper in the water and try to light it. It will not burn. Dip the paper in the
alcohol and it will burn. Now pour the alcohol and water together and dip the paper
money into the mixture. With the lights out, light the paper money and you will see a
purple flame, but the bill will not get burnt.
Concepts: the water is absorbed into the paper bill along with the alcohol. The warm
alcohol evaporates as a gas and burns outside the bill. The water keeps the bill from
getting warm enough to burn. The alcohol burns away before the water is all evaporated.
23. Drop the candle
Materials: A candle taped inside a clear rigid, large plastic cup, a match, a fire
extinguisher.
Demo: stand on a table and light the candle, holding it carefully. Have a big basket or
other adult to catch it as it falls to the floor. You should see the flame go out as it falls
before it gets to the floor.
Concepts: As the candle inside the cup falls, it is in free-fall. There are no gravity effects
when in free fall. No convection currents can exist, so no cool oxygen can come up into
the flame and the hot carbon dioxide gas can not rise up and get away from the flame. So
the flame products stay at the flame: Carbon Dioxide gas which quickly extinguishes the
flame. Notice that candle flames are tear shaped when not falling. A camera would see a
spherical flame on the falling candle as it would also be in the Space Shuttle.
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24. Upside-Down Tea Bag Rocket
Materials: dry tea bag and a match
Demo: light the tea bag from the top and watch. You should notice that it burns down and
the black ash will rise up right as the flame goes out.
Concepts: The heavy tea bag will sit on the table as it burns down. The hot flame sets up
a convection current, cold air rushing under the flame, hot air rising above the flame. As
the tea bag finally burns to a very light ash, the convection current carries the ash up with
it for “lift off”.
25: Typhoon Preparation:
Materials: Candles, matches, bananas and pecan slivers.
Demo: Blow out the lit candle and discuss the problems of needing light and emergency
supplies after a big storm. Then light the pecan stuck into the banana that looks like the
candle to the audience. Mention that some people forget to plan for emergencies and
would need food to survive. Then blow out your Special Candle, let it cool for a few
seconds, then bite the top off of it.
Concepts: Nuts with oil inside can burn and fuel a flame. We get the energy from the nuts
during digestion which takes a long time, but burning them releases the energy in seconds.
You can actually boil a bucket of water with the energy from a peanut.
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References and Acknowledgements:
Science teaches that behind every event in nature, there must be a cause. Seeing patterns
in nature is an essential part of understanding our universe.
I first saw many of these demonstrations when Dr. Tom Hudson presented them to the
Houston Clowns in July, 1991. They visit hospitals and cheer up patients.
I first presented a set of science demonstrations at a large public library in Del Rio, Texas
in August of 1991.
I first did a TTT of science demos to ASIJ teachers in Tokyo in the early 1990’s.
Frank Herbert was the featured speaker at the American Association of Physics Teachers
national meeting in Vancouver, BC, Canada. I enjoyed his speech and demonstrations.
He spoke with me and we attempted to get his TV science shows onto NHK education
TV channel with Japanese subtitles.
“Misconceptions in Science” is a very important study for all science teachers. It is now
taught to education majors and is constantly being discussed in our professional journals
and online.
 One interesting 3 page site has been attached for your reading
pleasure:Misconceptions in Science: E328: Elementary Methods.
 http://www.indiana.edu/~w505a/studwork/deborah/ accessed 10/29/05.
 Debi Hanuscin mentions “How can teachers best address student’s science
misconceptions?” She mentions structured experiences for students to “test out”
their ideas and prove correct concepts to themselves.

Her link to “Teaching for Conceptual Change: Confronting Children’s
Experience” is very informative.
Additional Demos from past Christmas Presentations:
Christmas Demos from 2007 by Mr. John O’Leary
Fun with Money:
1) Catch a Bill (free fall & reaction time)
2) Light a bill (evaporation & burning)
3) Coins
A) Why do some coins have ridges? (Newton-Warden of the Mint in England)
B) Which coins can float? (only the 1 yen coin from Japan)
C) Flipping coins with hear on a bottle (gas expansion with heat)
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Inertia (Newton’s 1st Law of Motion)
4) race a hoop & a disk (rotational inertia)
5) great soup can race (rotational inertia)
Candles
6) spoon (black from HC soot )
7) knife (whiff of steam)-----similar to us: eat HC & drink water, products:
heat,vapor/CO2
8) relighting candle (flame follows the hot air down)
9) candle put under a jar sitting in a pan of water (warm air cools/reduces volume)
Faraday (1826) had an entire lecture on the science of candle flames & wrote
them down with the urging of Charles Dickens.
http://www.rod.beavon.clara.net/Faraday_intro.htm
Air Pressure
10) Blow over a piece of paper—it lifts (Bernoulli’s Principle—low pressure, high speed
fluids cause low surface pressure, how things fly along with air forces)
11) Straws
A) 1 in & 1 out—hard to drink! (Atmospheric pressure: 14.7 lbs/in2) Fluids move
from high pressure to low pressure—weather!
B) finger on tip can lift water & it won’t come out! (low pressure above water &
how pumps work)
C) Lift a straw full of water out of the tank—how high can it get? (barometers)
12)Incredible Shrinking Mom (air pressure on our body)
http://www.geocities.com/CapeCanaveral/Cockpit/8107/shrinkwrap.html
Sound
13) Twirling tube (sound resonance, 4 octaves, Bernoulli’s Principle for air flow)
14) Standing waves in a water bottle ( standing waves, overblowing gives 3f, height
matters)
15) Play a song with the bottles (shorter columns yield higher notes)
More:
Christmas Demos Part 2, 12/2011 by John O’Leary
Physics of Motion
1) Cartesian Diver
Put an eye dropper inside a PET bottle full of water. When the PET bottle is
squeezed, the increase in pressure everywhere results in a smaller bubble in the eye
dropper, so it’s decreased buoyancy and increased density causes it to sink. Water can not
be compressed, only its pressure can be changed.
2) Coin on a hanger
A coin can be twirled on a bent coat hanger so that it will stay on the hanger when
spun in a vertical loop. The inward push of the coat hanger must be greater than the
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weight (force of gravity) to hold the curve without falling when going over the top. This
inward force is called Centripetal Force and it causes objects to turn.
3) Turkish Waiter brings you water
A glass of water on a tray may also be spun horizontally or vertically with out
spilling the water. The centripetal force of the cup on the water keeps it from spilling out!
This is also like turning corners on roller coasters and amusement park rides. You don’t
need that seat belt unless the ride stops when you are upside down.
4) Eggs and collisions
An egg is thrown into a sagging bedsheet & the egg survives without cracking.
The long impact time reduces the forces on the egg in this “soft” collision.
5) Bernoulli’s Effect and a breath of air
Hold a large bag to your mouth & blow out one time. See how much air that it
was. Now blow one breath but just outside the hole. Now many times more air goes in.
the low pressure of the fast flowing air allows room air to also move into the bag.
6) Stack of Cards
The static equilibrium of a rigid body is illustrated with a stack of cards which have an
impressive overhang.
MATERIALS: stack of cards, blocks or meter sticks
PROCEDURE
For a small audience, a deck of ordinary playing cards can be used. For a larger group, a
few dozen identical squares of cardboard or blocks of wood provide better visibility. A
more quantitative demonstration can be done with a stack of meter sticks which could
also be suspended in the form of a mobile[1,2]. The uppermost card of the deck is slid
horizontally until it is just about to tip over (half of it must be supported by the card
underneath). The top two cards are then slid in the same direction and so forth until the
uppermost cards hang out a surprisingly large distance beyond the base of the deck. For
more drama, let the stack hang out over the edge of the table[3]. The audience is then left
to puzzle over why the deck doesn't topple. A pair of card decks placed side by side and
sheared in opposite directions can be used to make an impressive, free-standing arch.
DISCUSSION
The rule is that the stack of cards is in stable equilibrium as long as the center of gravity
of all the cards above a certain point lies over a part of the card just underneath that point.
The center of gravity of the top card is at its middle, and so it can overhang by one half of
its width. When so placed, the center of gravity of the top two cards is such that the
second card can overhang by one fourth of its width. The third card can overhang by one
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sixth of its width, the fourth by one eight and so on (see the diagram). Thus the total
overhang of the top card in a deck of N cards is determined by the summation 1/2 + 1/4 +
1/6 + 1/8 + ··· + 1/2N, which is a harmonic series with a sum equal to 0.5(0.5772 + lnN)
for large N. Thus one can get an arbitrarily large overhang by using a sufficiently large
number of cards. With 52 cards, the maximum stable overhang is 2.27 times the width of
a card. In the presence of surface tension, which can be rather large if the cards have
smooth surfaces, one can achieve an even greater overhang than suggested by the above
calculation.
7) Spinning Eggs
In this “eggsperiment” you will use two eggs, one marked with an “O”, the other
with an “X.” Spin the egg marked with an “X.” Now stop the egg with your hand.
Immediately after the egg stops, remove your hand. Describe what happens.
Now spin the egg marked with an “O.” Again stop the egg with your hand and
then quickly release it. Describes what happens this time.
(Teacher's note: One egg is raw and the other is hardboiled)
Questions:
i) Why do think the two eggs behave the way they do?
ii) How could a cook make practical use of the results of this experiment?
8) Jar Accelerometer
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An accelerometer is a device that may be
used to determine the direction of an
object's acceleration. An accelerometer also
gives the direction of any unbalanced force
acting on an object. There are many types
of accelerometers. One of the simplest is
made out of a jar, a bobber and some
string.
Teachers Note:
To construct an accelerometer, glue a string to the
inside center of the lid of a jelly or peanut butter
jar. The length of the string should be slightly less
than the height of the jar. For reasons of safety, a
plastic jar is always preferable. Attach a plastic
bobber to the free end of string. After filling the
jar with water, with the bobber and string on the
surface of the water, place the lid on the jar. Now
tighten the lid and invert the jar. The bobber
should now be located just below the glass bottom
of the jar. If it's dragging on the glass bottom,
remove the lid and slide the bobber along the
string so that it is closer to the lid. You are now
ready to use your accelerometer.
Questions:
i. Hold the accelerometer in your hand.
Which way does the bobber point when
you are standing still?
ii. Which way does the bobber point as you
walk at a smooth, constant rate?
iii. Watch the bobber as you start from rest
and accelerate to the right. Which way
did it point as you picked up speed? As
you slowed down to a stop? You may
have to repeat this part of the experiment
several times in order to see all that's
going on.
iv. Repeat part (iii), this time accelerating to
the left.
v. How does the direction of the unbalanced
force you are exerting on the
accelerometer with your hand compare to
the direction of acceleration?
vi. Holding the accelerometer in front of you at
arm's length, spin in a circle. (Be careful
not to get too dizzy!) Observe the
direction in which the bobber is
pointing. According to the accelerometer,
what is the direction of the jar's
acceleration? In which direction are you
exerting an unbalanced force on the jar?
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This compilation is from Dec. 2011. Many were done for the P1-P4 classes
at OLY on 12/16/2011. More to follow!
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