Let our children_go_back_to_the_tradition_and_values_of_israel[1] (1)

Let Our Children Go back to the tradition and values of Israel

Introduction:

When it comes to education in Israel, there is a consensus that a real change
of concepts and of conducting the schools – is essential.

I've analyzed this issue according to the Theory of Constraints (-TOC) 1 and
found that the fundamental problem is: lack of challenges – which leads to boredom
and loss of interest.
The bored students do not usually see any connection between the learning
material taught to them and the life-skills they need, and so they act accordingly.

One area that suffers the most from this situation is Bible studies and the
Jewish Heritage.

The program suggested hereby, is a challenging one that combines these
areas with active experiences and experiments in Science.

Background:
Today, every learning subject/class is taught separately. The subjects are not
linked or connected in school. This way of conduct leads to preoccupation with
useless unnecessary details.
The conclusion I've come to – with the help of the book "Noise"2 – is that we
must "combine like terms", and "house" different subjects "under a single roof", as we
say in Hebrew. Thus, we minimize the noise made by insipid details.
To this many supporting references can be found. For instance:
In Humanities and related fields of knowledge, it is customary to gather details
into a story in order to raise and maintain interest in a topic.
The best way to ignite interest, curiosity and then creativity is to actively take
part in experiencing that thing.
Actively taking part in experiencing something results in fascination in it, and
is the core of Chemistry, Physics, Biology and the related subjects.

It was not for no reason that the people of Israel, standing in Mount Sinai said
“na’aseh v’nishma” (= we will do and then understand).

The program's principals:
The program is based on the following principals:
a) Approaching the topic by telling a captivating story/riddle/dilemma3. This
is done by using modern language the children could relate to, and by
1
The Theory of Constraints (TOC) is a management philosophy developed by Dr. Eliyahu M. Goldratt, author of
"The Goal", "It's Not Luck", "Critical Chain" and more. In recent years TOC is very popular in the high-tech and
business worlds.

2
Jacob Burak’s book Noise: The Profile of a Cultural Disorder deals with social behaviours.

All rights reserved to Dr. Rami Kallir Ltd ©

addressing deep familiar feelings4 – fears, doubts, insecurities, etc. – when
presenting the protagonist's problem. Each lesson's original story from the
Bible /Gemara /other-ancient-source is attached for frequent references to
be made during the lesson.
b) Structured guidance is given to students as to using TOC thinking tools so
that the find logical practical solutions to the problem, which they can then
inflict onto their own day-to-day lives.
c) Experiments and practical activities illustrate the logical solution, so at the
end of a lesson – the concrete outcome is an actual product.
d) The activities and experiments are very clear, structured and easy to
understand, so that any student/teacher/parent/grandparent can do them
with children, using tools and materials found in every household.
e) The program will be activated by direct instructive guidance, using
specially-suited kits and tools (-CDs, websites, etc.) to implement the
information.
f) The program will be activated in several versions: as an annual/semestrial
program according to age groups and different topics and subjects in the
Bible and in Jewish tradition; and as special days according to Jewish holy
days.

The program's concept
The combination of science and Bible studies makes a unique program that
merges, for the first time, humane aspects such as storytelling and theatrical acting
along side scientific experiments.
The program empathizes developing various thinking styles such logical,
critical and creative thinking.
Practical experimenting allows a heterogenic group of students to pleasurably
engage in scientific issues that are usually perceived as complicated and hard to
understand.
Many of the program's topics fit the formal education's curriculum, and can
enrich it with much-needed active, practical, fun experiences, that are currently absent
form science classes.
The program can be annual or semestrial.

The program's goal
1. Exposing the students to the connections and links between different
disciplinary fields of knowledge.
2. Developing and nurturing the children's curiosity, creativity and the drive
to discover.

3
"'The only way to understand the world', Magnus once said, 'is by telling a story. Science,' Magnus
said, 'only brings knowledge about how things are working. Stories supply understanding.' " – from
Marcel Möring's novel, In Babylon (Amsterdam: Meulenhoff, 1997) p.85.

4
As claimed in Bruno Bettelheim's book The Uses of Enchantment, published in 1976 .


Suggested topics5
1. Tohu va-Vohu – "…the earth was unformed and void" – the science of
Chaos – uncertainty as to what's to come – no control of time – building a
time-pendulum.
2. Ha-Mabul – "The Flood" – global warming – greenhouse affect –
ecological holocaust.
3. Moshe Ba-Teiva – "Moses in the bulrushes ark" – building Moses' ark –
floating on water – water proof materials and the surface tension of water.
4. Ha-Sneh Ha-Bo'er – The "burning bush"– low temperatures burnable
resins (– inflammable materials).
5. Mayim Min Ha-Sela – "water out of the rock" – identifying plants that
testify to the existence of ground water – water percolation – wellsprings,
siphons and wells.
6. Homot Yeriho Noflot – "and the wall fell down flat" – uses of energy of
sound – frequencies that crash rocks – ultra sound.
7. David and Goliath – the cumbersome physique of a giant; why smooth
round stones – the motion-energies of a sling.
8. Akeidas Yitzhak –Sacrificing Yitzhak – as sacrificing infants was
common, Abraham's greatness is to rebel against this.
9. Yosef Be-Mitzrayim – Joseph in Egypt – agricultural economy – how to
educate the people to properly keep and store their crops – making matzas.
10. Lag Ba'Omer – ridding of all inflammable things before the time of
summer heat-waves.
11. Hanukkah – using pure clear olive oil because it contains a lot of water
that decrease burning.
12. Esh Min Ha-Shamayim – "Fire from heaven" – lighting fire without
human touch.
13. Yaacov lays down on stones – right distribution of body weight.
14. Ha-Keshet Be'Anan – "And the bow shall be in the cloud" – features of
light: blue sky, red sunset.
15. Israelites and Philistines – technological society: processing metals, using
wheels, navigation and trade Vs. agricultural society.
16. David and Saul – different sounds affecting different moods: battle-cries to
lullabies.
17. Damning water – presence of parasites and germs in water – removal of
them with plant extracts, etc.
18. Producing wine, liquor, bread and cheese – the birth of technology.
19. Burning incense – repelling flying insects – ridding of lice with lavender
oil and rosemary oil.
20. Roll the stone from the well's mouth – protecting water's quality against
animals.

Workshops according to the Jewish holy days
5
The Biblical quotes are taken from the Mechon-Mamre translation of the Bible on the internet.


- Rosh ha-Shanah and Sukkot
1. Honey-dipped apples – preparing sweets with seasonal fruits.
2. Mathematics and Sukkah decorations – preparing unique decorations: Mobius
rings, spirals and more.
3. Hag ha-Asif – Time of Harvest – picking olives, oil retention, preserving
olives.
4. Come the rain and the bow in the cloud – the rainbow – mixing and separating
colors, white light and the colors of the rainbow.

- Channuka
1. Dreidels and optical illusions: making special dreidels with different spinnig
illusions, 2/3 dimentional, movement and color illusions.
2. Kaleidoscope: flexible morrors duplicate the candle light numerous times;
creating a kaleidoscope with a triple prism, to get a new colorful look on the
world.
3. Candles: why pure olive oil? – making colorful candles.
4. Shadows and colors: Do different light sources effect shadows? – building a
peeping box, and experimenting with different objects and sources of different
colors.
5. Glowing in the dark: activity in an invisible "ultra-violet" light with light-
emitting materials and phosphoric-color materials.

- Tu bi-Shvat and Family day
1. Spices and medicinal plants: etheric oils in plants – reviewing ways to extract
smells from plants and experiencing dissolving oil in different solvents. At the
end – preparing spicy fragrant oil in a little bottle.
2. Chemical garden: a spectacular garden of crystals in liquid. We will
demonstrate dissolvability of different materials in different solutions, follow
the differences between them, and each student will create his/her own
chemical garden.
3. Tastes and smells: how many tastes are there really? Four or four-hundred? By
making different favored drinks: a blue lemon drink; green strawberry drink,
etc.
4. Gel bracelets: using an amazing matter that absorbs water rapidly, turning it
into soft gel particals. At the end we make a spectacular gel bracelet.
5. Pattern and models: between art and science – students make their own palm-
pattern with special matter which solidifies in one minute. Pour calcium
sulfate into it – and get a palm model of their hand.

- Purim
1. Balance: What laws of physics allow an acrobat to walk on a tight rope
without falling? – The activity will revolve around balance and momentums.
2. Making make-up: What conditions are necessary to produce make-up colors?
– How to add oil-based-pigments to water-based-materials?
3. Optical illusions: Creating optical illusion with a ball and an induction coil.
We will check how our eye-brain connection can change the way we see
things; and create optical illusions of non-existing movement.
4. Periscope: How can the features of light be used to see beyond obstacles and
opaque matters? Mirror games: building a special periscope that enables front,
rear and side sights.


5. Noises and Sounds: How does sound turn into movement and movement –
into sound? – Features and qualities of sound: how does sound travel, how is it
formed, and how is it received by our ear? – We will make rain-sticks, rattlers
and more.
6. Glupie: un-sticky glue – How can we take glue and turn it into a soft lump that
is not sticky? A chemical experiment that fascinates everyone! Mixing
colored-glue with a special kind of material that makes it viscous, and the
result is a new, limber, nice-to-touch matter that's fun to play with!

- Passover – Pesach
1. The great Heat Waves: activities for days of great heat waves: Static
Electricity balloons sticking to walls, "stand straight" hair, paper dolls, neon
light turn on without an electric current flow, and more.
2. How do detergents work: Get to know the unique qualities of soap, and make
colorful fragrant cosmetic soap.
3. The Smell of Spring: How to get odors form spices and perfume-plants – we
will review different ways to do so, and make perfumed papers, fragrant
drinks and spice-oiled bottles.
4. Big soap bubbles: making big soap bubbles takes more than mixing water and
soap… other materials influence the bubble's flexibility and durability.

- Lag ba'Omer / Yom ha'Atzma'ut(=independence day)
1. More than a Bow and Arrow: building and launching "rockets" with no flames
involved. The rockets ascend several meters up.
2. The Colors of Fire: fire contains all colors. The three primary colors – what
happens when you mix them? Can you separate them back again? Breaking
the white light into colors with the help of prisms.
3. Iridescent Fire: at the end of the activity we have a water-oil colorful test tube
illustrating the mixing and separation of colors.

- Shavu'ot
1. SAP (– special Absorption Polymer) turns liquid into gel: How can you turn a
glass of water up-side-down and not spill a drop? – use an amazing water-
absorbing matter that turns it into soft little "grains" of gel. The children get to
know SAP while experimenting with it, and fill-up a test-tube with colorful
gel-layers.
2. Flying tray: how can we transfer water from one place to another without
spilling it? – The wonders of the centrifugal force.
3. Siphons and Archimedes' cup: how the Greek ancient wise man prevented
wasting expensive drinks and spilling them on the floor.
4. Milk and its products: Making cheese out of pasteurized milk by adding a few
drops of lemon juice to it.

Moses in the Nile – Floats or Sinks


Equipment:
Each kit contains:
5 bowls, 5 bags with different materials for buoyancy (=floatability) test:
stones, pieces of Styrofoam, pieces of wood, glass marbles, pieces of
plasticine, corks, iron nails, pieces of aluminum, pieces of cloth, sponges,
pieces of papyrus plant; wax candles, papers, a small carton model of a boat, a
little doll.

Goals:
Get to know the features determining the buoyancy(=floatability) of an object.

Terms:
light, heavy, floats, sinks.

Theoretical Background:
When referring to the features and qualities of materials one often comes
across expressions such as "Aluminum is a light metal" or "Carbon Dioxide
(=CO2) is a heavy gas". To compare heaviness or lightness between two
materials, we must make sure other variants such as volume, temperature and
pressure are equal.
The ratio of Mass under prescribed conditions of temperature and pressure is
called "specific gravity" or "density".
Density is a measure of how much mass is contained in a given unit volume
(density = mass/volume).
In a given cubic volume a small amount of particles indicates low density, and
a big amount of particles means high density.

Examples for the density of several materials:

material density
Air 0.00129
Water 1
Iron 7.8
Aluminum 2.7
Alcohol 0.79
Ice 0.93
Honey 1.35
Olive Oil 0.9

Since the density of water is 1 (gram/cc) it is customary to compare
density of materials to that of water. The density – also referred to as "specific
gravity" or "specific weight" – indicates an object's ability to float.
When an object's specific weight is lower than that of the liquid it is in
– the object will float; when its specific weight is higher than the liquid's –
object will sink; when it is equal – object will hover in the liquid.

There's often an erroneous premise that the floatability of matters is
affected by their state (- gas/liquid/solid) or their viscosity. For instance, a
liquid such as oil – which has a specific gravity lower than water's – will float


on it. Solid wax will also float on water, for the specific gravity of solid wax is
lower than that of water.
When an object consists of several different materials, its specific
gravity (= density) is determined by its total weight divided by its volume. An
object filled with air will have density lower than one, and will float on water.
That is why ships can float on water. Iron and other heavy metals form
their structure, but their volume is big and filled with air.

Scientific thinking with the TOC thinking tools:

Moses in the Box in the Nile

Many years ago, the people of Israel resided in Egypt. Many days they
were living in a foreign land, and one day an Egyptian king was crowned, and he
enslaved them. In-spite of the hard work, the Israelites' numbers increased
consistently. King Pharaoh searched for a way to decrease their numbers, and so he
ordered to throw into the Nile every Israelite born son.
One of the Israelites was Amram, who had a wife – Yocheved, a son –
Aharon, and a daughter – Miriam.
Yocheved gave birth to another son, but could not bring herself to killing him
as the king's order demanded. She hid her baby-boy in the house for 3 months, till it
was too difficult to keep doing so.
Let's look at Yocheved's conflict from through the TOC conflict-cloud
diagram:

Obey order (=throw Protect the rest of
baby in the Nile) the family

Protect the
whole family

Disobey order (= Protect the baby
hide baby at home)

The way to evaporate this conflict cloud: she decides to stop hiding the baby,
but not to throw him in the Nile as he is, but place him in a woven box.
"And when she could not longer hide him, she took for him an ark of papyrus,
and daubed it with slime and with pitch; and she put the child therein, and laid it in
the flags by the river's brink." (Exodus, 2, 3).
She weaves a box of papyrus. Papyrus is a water plant with upright stems. The
stems contain air, and therefore float on water. Papyrus was accessible since it
naturally grows on river banks.
Another advantage of this plant is that it's a flexible material and so a box
made of it, should it come upon a rock or a branch – it won't break, but merely fold. A
similar box made of wood – might break.


The disadvantages are: the box is not totally sealed. It is a sort of a woven
basket, into which water can enter and wet the baby. Moreover, after a while the
papyrus absorbs the water, and the box could sink.
Yocheved is aware of the advantages and disadvantages of her material of
choice.
She solves the first problem by coating the inside of the box with clay, that
fills-up gaps and empty spaces, and prevents water from penetrating and wetting the
baby. She also covers the outside of the box with pitch, which is an oily substance that
prevents water form being absorbed by the papyrus.
Yocheved puts her son in the box, and the box in the river. She appoints his
sister Miriam to be his sentry and be on the lookout for him.
The baby floats down the river and reaches Pharaoh's daughter's bathing area.
Pharaoh's daughter takes pity on the infant, and decides to adopt him and rase him as
her own. She names the baby "Moses".
His sister, Miriam, suggests the adopting princess to take a wet nurse from the
Israelites to breast feed him – who is non other than Yocheved – and by that the baby
is actually returned to his original family for a while. Later on he goes back to being
brought-up in the king's court.
Now, let's take another look at Yocheved making the box with the TOC tool
called "the Ambitious Target" (AT).

AT: Saving the Baby
Obstacles Intermediate Objectives
If put in the river – baby will drown for it cannot Make baby float by putting him in
float nor swim a box made of something lighter
.than water
Use accessible available material
.Materials to make the box are hard to come by
.that doesn't cost anything
Box can hit a rock or branch and break
.Use flexible material
A papyrus box is like a basket which allows
.Fill-up empty spaces with clay
.water entrance so the baby would get wet
Water will be absorbed by the box and it'll sink Cover the outside of the box with
.water-proof matter
Baby cannot survive for iternity in the box Place the box in the river so it'll
.sail to a safe place
Unexpected things may happen Let his sister be on the lookout for
.him

The next experiments will demonstrate the different density of different
objects, which is reflected by the objects' buoyancy. We will try to change the specific
gravity of the objects, and by that to influence their buoyancy.
We will examine that by experimenting on different objects, the human body,
and by changing a doll's center of gravity.


Experiment number 1: floats or sinks
Goal: Estimating objects' buoyancy and then testing it.
Equipment (– for a party of 4 students): a bowl, a bag containing: stones,
straw, pieces of paper, pieces of Styrofoam, pieces of wood, glass marbles, Plasticine,
corks, iron nails, pieces of aluminum.
Procedure:
1. Students take a close look at the materials, and speculate which
will float and which will sink in water.
2. A table such as this may assist students to organize information:
Name of object / Materials Speculation: will object float Result: did object
object is made of ?or sink in water ?float or sink

3. Fill bowl up with water.
4. Place the objects in the water, and check whether the results
mach the speculations, and add result data to table.

What happens and why:
Materials containing air, such as Styrofoam, corks and wood, have low
density, so they will float on water.
Materials like glass, metal, stones, that have high density – will sink.
Materials such as paper, sponges, etc., also contain air, but water will
penetrate fairly easily, replace the air, and make them sink.

Experiment number 2: floats but sinks
Goal: Increasing an object's specific gravity so that it would sink.
Equipment: same as in experiment No.1 .
Procedure:
1. Ask students to take objects that floated, and make them sink.
2. Examine the different techniques students used in order to sink objects.
Possible examples: attaching Plasticine to wood or Styrofoam,
inserting nails in corks. If we take an object with density lower that that of
water, and attach to it an object more dense than water, we will get a new
object, with density depending on the materials creating it. If the specific
gravity of the new object is lower than that of water – it'll float. If it is higher –
it'll sink. Using that enables us to sink floating materials.
In experiment No.2 we saw that some objects contain air, and therefore
float. But when water replaces the air, the specific weight increases, and the
objects sink.


Experiment number 3: sinks but floats
Goal: Decreasing an object's specific gravity so that it would float.
Equipment: same as in experiment No.1 .
Procedure:
1. Ask students to take objects that sank, and make them float.
2. Examine the techniques used by students to make objects float.
Possible examples: sealing both ends of plastic straw, so air is caught
inside; attaching Styrofoam to an object that sank; flatten Plasicine and shape
it like a little boat.
As in the prior experiment we created a new object out of several
materials and air. If the new object's specific weight is lower that that of water
– object will float; if its specific weight is higher – it'll sink.

Experiment number 4: applying wax to paper
Goal: preventing water from saturating the paper.
Equipment (for each student): pieces of paper, wax candles.
Procedure:
1. Hand out pieces of paper and ask students whether one of the former
techniques will be efficient for paper to float on water.
2. Hand out wax candles. Each student will rub wax over paper, creating
a thin water-proof layer on both sides of the paper.
3. Place wax-covered paper and see if it sinks.
In experiment No.1 we saw that the paper first floats, and then sinks.
That was due to the paper's fibers being saturated by water. Air went out and
water in, so the paper sank. In order to make paper float, we must prevent
water from penetrating.
Covering paper with wax shuts the tiny holes in the paper, and
prevents air form escaping and water form entering. Moreover, wax itself has
low density (- as was demonstrated in Experiment No.1 when the candle
floated).

Experiment number 5: floating boat
Goal: creating a boat that won't sink.
Equipment (for each student): a carton board boat model + instructions, a
small doll, wax candle, Bristol board or wax paper.
Procedure:
1. Rub wax candle over bottom and outside of boat model.
2. Assemble boat according to model-building-instructions.
3. Place doll in boat, and then – boat in water, and sail it.
Boats and ships are usually made of materials that have higher density than
that of the water they displace. In spite of that, they still float. The reason is
their structure, which is essentially a hollow hull filled with air. The total
density of the vessel is lower than 1 (– which is water's density), and so it
floats on water.


David and Goliath

Biblical Story:
The Israelites stand timid and helpless against the Philistines. The
philistines have several advantages, one of which is mastering the arts of
metal-processing and of using horses and chariots. That meant the Israelites
were inferior to the Philistines when it came to combat battling.
Moreover, the philistines have Goliath – a fearsome powerful giant
with a shiny armor and vast military experience.

"And there went out a champion from the camp of the Philistines,
named Goliath, of Gath, whose height was six cubits and a span."
(Saul A, 17, 4)

And Saul said to David: 'Thou art not able to go against this
Philistine to fight with him; for thou art but a youth, and he a man of war
from his youth.'
(Saul A, 17, 33)

David is facing a conflict: to-fight or not-to-fight Goliath.

To Fight Goliath Win the battle

Survive

Not to Fight Avoid personal
Goliath risk

The premises behind the dictums:
a) Victory over Goliath will determine the war's fate.
b) Avoiding personal confrontation with Goliath increases David's
chances of survival.
c) David is very likely to loose to Goliath.
Against the common opinion around him, David decides to accept
Goliath's challenge. King Saul gives him a sward and armor – the same
weapons as the ones used by the Philistines, but of inferior quality.
David wants to fight in a way that would let him benefit from his
advantages, and not this "modern" way in which Goliath has the upper hand.
So, David dismisses the royal weapons, and chooses over it his shepherd's
sling and some round smooth river stones.
So it won't be a head to head combat, but David will have the advantages
of speed and accuracy and of using the distance from Goliath.


Goliath looks down on David because he is so young and small, and also
because of his weapon of choice – a sling is considered ineffective and
inaccurate, and Goliath is well protected behind his armor. There only a single
exposed spot – on his forehead – much like Achilles' hill.
The usage of stones and weapons is an ancient one. In the story of
"Pilegesh Ba-Giv'aa" (– the mistress in the city of Giv'aa) some 700 men of
the Binyamin tribe (tribe of king Sual) gathered. Alongside men of sword
were a lot of stone throwers:
"All this people, even seven hundred chosen men, were left-handed;
every one could sling stones at a hair-breadth, and not miss."
(Judges, 20, 16).
It is very probable that other tribes had some skilled stone throwers as
well. But still slings and stones were considered inefficient – see Yehuda
Ziv's interpretation about it.
That leads us to believe that David had further knowledge of stone
throwing, knowledge that gave him a significant advantage over Goliath.

David's challenge would be: fighting Goliath while avoiding personal
risk, as best he can.
"And David said unto Saul: 'I cannot go with these; for I have not
tried them.' And David put them off him.
And he took his staff in his hand, and chose him five smooth stones
out of the brook, and put them in the shepherd's bag which he had, even
in his scrip; and his sling was in his hand; and he drew near to the
Philistine…
…And it came to pass, when the Philistine arose, and came and
drew nigh to meet David, that David hastened, and ran toward the army
to meet the Philistine.
And David put his hand in his bag, and took thence a stone, and
slung it, and smote the Philistine in his forehead; and the stone sank into
his forehead, and he fell upon his face to the earth.
So David prevailed over the Philistine with a sling and with a
stone, and smote the Philistine, and slew him; but there was no sword in
the hand of David."
(Saul A, 17,39-50).

David has experience in using a sling and smooth round river stones, and he
appreciates the virtue of their accurate move in the air.
When a stone, any stone, is thrown, a number of forces are applied on it,
causing it to move in several directions. The distance and accuracy that the stone
reaches are the result of adjusted calculation of all forces applied on it.
The initial velocity is derived form the force applied on the stone until it
leaves the hand or the sling. The sling is used as a lever-arm to enhance the force.
Other factors are the mass (-weight) of the stone, friction with air, earth's
gravity, and moving around axis that decelerate and stop, and often divert forward
movement.
David's knowledge became common knowledge, and the sling is also known
as "shepherd's sling" or "David's sling"' and unfortunately a lot of our IDF soldiers
have been hit and injured by stones shot from these slings.


Physical background:
The movement of any body – excluding one of atomic sizes – abides by
Newton's laws of physics. Specifically, by his second law:
Force = mass * acceleration F=m*a .
We will break down the movement of a thrown body into segments, and
determine for each segment what the leading parameters are. For the sake of
simplicity, let us look at a ball game that's being thrown.
Segment A: the ball is at rest, so its initial velocity v0 = 0.
The hand muscles apply force (=F) on the ball for a period of time (=t). the
ball leaves the hand at a speed of [vt] which is considered its final velocity, because
since the time the ball has left the hand – no force is applied on it, and the ball will not
accelerate any more.
The final velocity (vt) is, therefore, the multiplication of acceleration (a) by
time (t): vt = a * t .
The lighter the body is, which means the smaller its mass is – the easier it is
for us to apply greater force on it.
Be it that our force is limited, we can obviously only throw bodies that weigh
up to a certain weight.
Segment B
: the ball is flying in a certain orbit till it hits the ground or an obstacle. From
the moment the ball leaves the hand the throwing-force no longer affects it. Three
other forces do:
1) Gravity – a force that pulls the ball down, towards the ground
causing the ball's orbit to be an arched one.
2) Friction – the friction of the air causes deceleration.
Deceleration is the opposite of acceleration.
3) Fluctuations - various fluctuations that move the ball round and
side ways, at the expense of moving forward.

Segment C: the Hitting Phase, which is rapid deceleration.
Deceleration is actually negative-acceleration. So the formula remains the
same, only reversed directions: -F=m*(-a) .
The heavier the body is, the greater the force is, and the harder it is to stop is.

Activity number 1: the Effect of Mass and Shape on Movement
To quickly throw objects of great mass, a lever is used. Our hand is a lever,
but when it comes to hitting a ball – the baseball bat or golf club extends the lever-
arm, enhancing the hitting force.
Using a sling also extends the lever-arm as well as the time of acceleration, so
that the stone sets off at a greater speed than when it leaves a hand.
The catapult is the device used in ancient times – till canons were invented –
to shot massive stones at fortified cities.
In this day and age of automatic weapons, rockets and missiles, at the verge of
laser and sound-wave based death rays, some do not think much of sling-shots, but it
is important to keep in mind that wars are not just a recent phenomenon, and a stone
shot from a sling can cause death and severe injuries, much like a gunshot.


For the sake of safety, we will use only Plasticine or soft clay.

Equipment:
For the Catapult: Plasticine, doctor's sticks (for throat culture, etc.) flat
saucers, scotch-double-sided-tape
A pencil or another straight thin stick to be used as a hinge,
Open space to practice throwing,
Targets – preferably ones that the Plasticine will stick to.

Procedure:
1. Make a sling out of the stick and the saucer according to this diagram:

2. Put our little catapult on a pencil or such object for it to be the hinge of the
lever-arm.

3. Place a little Plasticine ball on the saucer, and flick other end with your
finger. The ball will "fly" in an arched orbit towards target.

4. It is possible to use one hand as the hinge, as the other hand flicks the stick.
That way the force is greater, and the balls can fly horizontally.

5. Arrange a shooting practice range where students must shot into boxes or
other targets.

6. Make balls different-sized balls: small, medium and large and check which
one "flies" the furthest.
7. Make from similar sized balls different-shaped "bullets": ball, disc ,snake,
pyramid and so on, and check how an object's surface affects its "flight".
The more symmetric the shape is – less energy is lost to friction, and the better the
object "flies".

Activity number 2: Using a Sling to Shoot Plasticine Balls
Equipment:
Plasticine,
1 meter of wide-gift-wrapping band,
Targets – preferably ones that the Plasticine will stick to.

Procedure:


1. On one end of the wrapping band, make a loop-hole wide enough for a
wrist.
2. On the other side tie some knots, to ensure good hand-grip.
3. Fold wrapping-band symmetrically, so both sides are of equal length.
4. Insert wrist into loop-hole, and hold other band-end in that very hand.
5. Go out to the shooting range and aim for the targets.
6. Place the Plasticine ball in the middle of the band – where it is folded.
7. Turn the band holding the Plasticine ball faster and faster, until it
seems to fly at the target you're aiming for, and then – open your hand,
let the band go and the ball fly towards the target.
8. Repeat this activity till some sling-shooting skill is obtained.
9. We realize that the ball does not always fly as we intended, so we learn
to appreciate David and the skilled biblical shepherds.

Activity number 3: Following the Ball's Move in the Air
Equipment:
For each student:
A rubber ball(– or Plasticine to make balls from – that will shorten the
throwing distances, but will be a much more economic solution),
Gift wrapping band,
Scotch tape,
Targets.

Procedure:
1. With the scotch tape, attach a gift-wrapping-band "tail" to every ball.

2. Throw the ball in different angles: acute, obtuse and right angles.
3. We notice that the more obtuse the angle is – the flatter the arch of the
orbit is.
4. A vertical throw has the longest time-span.
5. "Catch the tail" game: First, students pair-up. Then, in each pair one
student throws the ball while the other has to catch it by its "tail" (-
wrapping band) as far from the "head" (-ball) as possible.

Activity number 4: Energy Loss: How Shape Effects Throwing Distance
When a smooth, round symmetrical river-stone is thrown, it'll turn around one
axis, maintaining its turning direction, and its kinetic energy.
When a common asymmetrical stone is thrown, it'll turn around several
axes, each time in a different direction, so the turning direction will differ, the
kinetic energy will decrease, and the stone will soon drop, never reaching its
target.


Equipment:
For each student:
Targets.

Procedure:
Now that we are aware of the significance of throwing angle, let us
mark some distance-units and targets in our field/open space.
Take some Plasticine, and shape the exact-same amount in different
ways: ball, egg, disc, cone, etc.
Each time shape the Plasticine, and throw it, aiming at the target, to see
which shape reaches the farthest. The best way to conduct this experiment
would be to re-throw similarly sized and shaped Plasticine lumps, and write
down the results to get the average from.
It will show that the ball, or – like the American football's ball – egg
shaped lumps go the longest distances.

In the next experiments we will try to understand why the smooth,
round symmetrical river-stone is more accurate than others.

Activity number 5: Dreidels
Goal: Getting to know the different factors affect a dreidel's movement.

Background: Why bicycle in motion does not fall is a question difficult to
answer for many students of physics… until they perform experiments with
gyroscopes.
In-fact, it all comes down to Newton's first law of motion, that states that
"Every object persists in its state of rest or uniform motion in a straight line, unless it
is compelled to change this state by forces impressed on it."
It is easy to understand this when dealing with an object moving in a straight
line: it takes force to move a rested object. It also takes force to divert a moving
object, and also to stop a moving object.
This is the law of conservation of linear momentum. But for an object
rotating, the conserved momentum is that of the axis or plane of rotation.
That explains why a dreidel will be leaning on its side when "standing" still,
and will stand on end when spinning.
And this demonstrates the law of conservation of angular momentum.
The two forces impressed on the spinning dreidel are earth's gravity verses the
momentum's conservation.
Usually there are some disturbances due to energy loss or unequal weight
distribution.
The verbal and mathematical explanations for the movement of a dreidel or a
gyroscope are not simple. We will try to overcome their complexity with several
experiment in which we will deliberately make different changes and test each time
how those changes affect the dreidel's circular motion.
It is important to note that we have no means to measure the dreidel's spinning
speed, so our test is one of quality.


Dreidels and Conservation

Equipment:
Carton disks with a hole in them
Glass marbles and some insolating tape (- duck tape),
Or: beads and half a skewer.
Some crayons and stickers for decorating purposes
Plasticine.

Procedure:
Preparing a Dreidel:
Insert the glass marble into the disk's hole, and cover one side of it
with the duck tape, or
Slide the half-a-skewer through the bead's hole and place the carton
disk on the bead so the skewer is facing down.

To see what affects the motion of a dreidel, we will perform some changes,
checking how each one of them affects the dreidel's motion.

Experiment 5/1: Friction
Friction is created when two objects come in contact, and at least one of them
is moving. Here, the objects are the dreidel and the surface on which it is turning.
The fewer points of contact there are, the smaller the friction is, and the longer
the dreidel saves its kinetic energy, and therefore keep on spinning longer.
How can we reduce friction? – The change can be made to the surface or to
the dreidel itself.
a) Changing the surface: place the dreidel on a surface such as a
smooth table, a floor, a sandy ground. Check which one
makes the dreidel spin for the longest time.
b) Changing the dreidel: the smaller the dreidel's-surface-area
touching the ground/surface is, the smaller the friction is.
Since the marble/bead is round, it should have but one point
of contact with the surface, causing minimal friction.

Experiment 5/2: symmetry around spinning axis
The weight distribution around the spinning axis must be equal, or else, the
dreidel will quickly lose the energy given to it. Symmetry is changed by tilting the
carton disk, or by adding Plasticine on one side of the dreidel only.

Experiment 5/3: weight distribution
The heavier the weight at the disc's periphery is, the longer the dreidel will
spin. In the equation of linear motion, the momentum equals mass times velocity. In a
circular motion, the circular momentum is set by the multiplication of the momentum
– hence, lever-arm length times the weight – and the rotating speed.


The faster the spinning speed is, the bigger the circular momentum is. The
bigger the wheel is, the greater its stability is. The better the weight is distributed in
the periphery, the more stable the wheel is.
A typical example for that are the bicycle wheels. Bigger wheels are more
stable than smaller ones. The weight distribution is also very clear when looking at
bicycle wheels – the weight is mostly in the periphery.
It is advised to compare two dreidels of the same size, and 8 equal pieces of
Plasticine.
On one of the dreidels add 4 pieces of Plasticine to its center, and on the other
– add 4 pieces to its periphery area.
In this sketch, the dreidel on the right is more stable than the one on the left.

Activity number 6 –round smooth river stones (=r. s. river stones)
vs. common stones
Equipment
Several round smooth river stones (=r.s.river stones)
Several common stones

Procedure
Carefully choose several r.s.river stones and several common stones. Try and
spin all stones for as long as possible. It will become clear that the r.s.river stones are
much more capable of spinning; and that the more symmetric the stone is – the longer
the spinning will last.

Note:
Since symmetric r.s.river stones are hard to come by, we will use hard boiled eggs for
the next experiments.
Boil an egg with some salt. The salt keeps its shell from cracking while it's
cooking.

Experiment 6/1: Spinning a Hard Boiled Egg
If we take a dreidel and try to make it stand on end, it'll tip over onto its side.
But if we spin it, it'll stand on end for some time, even though it will be
standing on one single point.
A hard boiled egg will do the same. If we try to make it stand on end still,
balanced, it'll roll over on its side. But if we spin it – it'll rise up and stand on end.
How does the spin make the egg stand on end?
When an object rotates, it creates a physical effect called "angular
momentum". The angular momentum has a direction – the direction of the axis of the
spin. The spinning object abides by the law of conservation of angular momentum;
hence, for an object to change its state, a force must be impressed on it.


If we spin the hard boiled egg at great speed, we will see it raising-up,
spinning standing on its end. The faster the egg spins, the greater the angular
momentum and the longer the egg will rotate standing on end.
The spinning egg traces out a little circle. The more symmetrical the stone is,
the smaller the circle. Several factors affect an object's symmetry; for instance, the
inner weight distribution – every egg contains an air bubble that alters the egg's inner
weight distribution.

Experiment 6/2: Comparing Velocity and Spin Duration.
The angular momentum is better kept, the more symmetrical the stone is.
Since we have several eggs, we will spin them and measure the spin durations and
notice a slight yet significant change from egg to egg. Moreover, we shall crack one
of the eggs and take out a small piece of its shell. That egg's spin duration will
immediately change.

And… a Story
In addition, here is a story that was published in "Einayim" (= "Eyes")
magazine. It was written by us and is related to the subject.

A Competition of Weights:

When we were children, we used to play outside. We had a "hit the target"
game. We would pick an object such as a barrel or a big rock, and try to shoot stones
at it.
At first, I wasn't very good at it. The stones I threw always landed too close,
and I thought it was due to my poor aiming, or lack of strength.
To improve my scores, I had collected some grovel stones and practice in our
back yard.
One day my dad saw me throwing stones and hitting nothing. He looked at the
little stones I was holding, and handed me one that was bigger. "Here, try this one," he
offered.
I held his stone in my hand. It weighed a lot more than my stones. I thought I'd
have to use a lot more power to throw that one.
So I tried my best, and threw it as hard as I could. It landed very far. I had no
idea I was that strong. I picked it up and aimed again. This time, I didn't try that hard.
I concentrated, threw and hit it!
I tried once more, and I struck again; and the next time.
I concluded it had something to do with that stone being heavier than the
grovel stones. I found an even heavier stone.
I held the heavy stone in my hand, concentrated, aimed, threw it… and it
landed so close to me, it nearly hit me.
That day I searched for no explanations to it all. I jest kept on practicing with
the medium-weight stone.

A few years later I learned in physics class about persistence and friction.
Persistence is a quality that every body or object in the universe has. It means
that the object will continue moving (or resting) in the same manner, unless we
impress on it a force that would move it otherwise.


Persistence is dependent on an object's mass. The lighter the object is – the
easier it is for us to move it; hence – the lower its persistence is.
And vice versa: the heavier the object is – the higher the persistence.
That explains why it was so difficult for me to throw the heavy stone. I had to
use a lot of power to overcome that stone's persistence.

Friction is a force that exists between two objects that are in contact with each
other. If one of the objects is in motion, friction will slow that motion down.
When a stone goes "flying" in the air, there is friction between that stone and
the molecules of the air. If the friction of the stone is high – the stone will move
slowly.
The smallest stone was not heavy therefore its persistence was low. But as
easy as it is to throw it is to be stopped. That's why I couldn't throw it very far.
The medium weight stone is in between – it's not too hard to throw, and not
very easily stopped.

To try it for yourself you could make three balls of Plasticine:
A small sized one – the size of a fingernail;
A medium sized ball – the size of your thumb;
A large ball – as big as your fist.

Take a flexible plastic spoon to be used as a sling.
Place one ball on the spoon and hold its handle in one hand. Carefully bend
the spoon with your other hand on the other end… and let that hand go.
The ball will go flying in the air.
Do the same with all three balls, using equal force.
Check which of the three balls reached the farthest.


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